The correct answer is option C, The narrator's platoon was surrounded by the enemy, similar to the way the narrator feels when he is surrounded by his family
Reason - 
In the story by Tim O’Brien’s, It is clear that the narrator is puzzled at two instances and at these two instances the word "Ambush" relate to its title The two instances are given below:
a)	The first instance is when the narrator’s daughter is asking him question about his war time memories. The narrator feels guilty when he lied to his daughter in order to be a hero in front of her but somewhere he was aware that he was lying.  
b)	The second instance is when the narrator threw a bomb and killed a soldier of another nation. He is guilty about killing anyone during wartime.  
 
        
             
        
        
        
Energy and matter characterize both physical and biological systems. These systems are defined both by the types of energy and matter they contain and by how that matter and energy move through and between systems. ... This means that energy and matter can change forms but cannot be created or destroyed.
        
                    
             
        
        
        
The answer is D, increasing genetic variation
        
             
        
        
        
Answer:
Normal Strand: alanine - methionine - histidine
Mutated Strand: glutamine - cysteine - no third amino acid.
Explanation:
<h3>mRNA Structure</h3>
Messenger ribonucleic acid (mRNA) is the RNA that is used in cells for protein synthesis. It has a single strand made by the transcription of DNA by RNA polymerase. It contains four nucleotides: Adenine (A), Guanine (G), Cytosine (C), and Uracil (U). 
<h3>DNA Replication</h3>
Before transcribing, we need to create the complementary strand of the DNA. We're going to write out the nucleotides of the complementary strand by matching the nucleotides in these pairs: (A & T) and (C & G). 
               Normal Strand: GCA ATG CAC
Complementary Strand: CGT TAC GTG
Next, we can transcribe this to find our mRNA. We're going to do the same thing to the complementary DNA strand, but with Uracils instead of Thymines. So our pairs are: (A & U) and (C & G)
Complementary DNA Strand: CGT TAC GTG
                         mRNA Strand: GCA AUG CAC
You'll notice that the mRNA strand is almost exactly like the new mRNA strand, but with Uracil instead of Thymine.
<h3>Reading Codons</h3>
Each set of three nucleotides is known as a codon, which encodes the amino acids that ribosomes make into proteins. To read the codons, you need to have a chart like the one I attached. Start in the middle and work your way to the edge of the circle. Some amino acids have multiple codons. There are also "stop" and "start" codons that signify the beginning and ends of proteins.
mRNA Strand: GCA AUG CAC
 Amino Acids:   Ala   Met   His
Our sequence is alanine, methionine, and histidine. 
<h3>Frameshift Mutations</h3>
A frameshift mutation occurs when a nucleotide is either added or removed from the DNA. It causes your reading frame to shift and will mess up every codon past where the mutation was. This is different than a point mutation, where a nucleotide is <em>swapped</em> because that will only mess up the one codon that it happened in. Frameshift mutations are usually more detrimental than point mutations because they cause wider spread damage.
<h3>Mutated Strand</h3>
Let's repeat what we did earlier on the mutated strand to see what changed.
               Mutated Strand: CAA TGC AC
Complementary Strand: GTT ACG TG
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Complementary DNA Strand: GTT ACG TG
                         mRNA Strand: CAA UGC AC
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mRNA Strand: CAA UGC AC
 Amino Acids:   Glu   Cys   X
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Our amino acid sequence is glutamine, cysteine, and no third amino acid.
As you can see, removing the first nucleotide of the strand caused every codon to change. The last codon is now incomplete and won't be read at all. If this happened in a cell, the protein that was created from this mutated strand would be incorrect and may not function completely or at all.
 
        
                    
             
        
        
        
They are reactants because they are present before the reaction