The answer is letter
D.
<span>
Economists often use
the aggregate supply and demand model to reflect the total amount of goods and
services required at all possible price levels during a specific period. It
reflects the overall price of foods and services in an economy for a given
period and is often illustrated with the supply-demand curve. This shows the
relationship between price levels and quantity of output that a particular firm
is willing to provide to the general public.</span>
        
             
        
        
        
Answer:
Amino acids are the building blocks or monomers of proteins. These are the molecules that act as the precursors for the biosynthesis of various hormones some other molecules of our body. these amino acid molecules for by the process of protein synthesis.
The given amino acids are precursors of the following molecules-
1. Histamine - Histidine
2. Epinephrine - Tyrosine
3. Serotonin - Tryptophan
4. Glutathione - Cysteine, Glutamate and Glycine
5. Heme - Glycine
6. NAD(H) - Tryptophan
 
        
             
        
        
        
Answer:
why an athlete would need to be concerned about twitches or contractions is because, whenever they perform, and such thing happens, it will most likely distract the athlete, and cause the athlete doing his/her performance to not be as good, and may lead to failure, for example, when someone is running very fast for a sprinting race, and he has a contraction in his leg it will cause him to react by showing signs of pain by slowing down or even tripping and falling, causing him to lose the race. 
Hope this Helped!
 
        
                    
             
        
        
        
Answer:
Because enzymes have many functions as chemical catalysts in numerous chemical reactions (for example in metabolism). By lowering the activation energy, they make it much easier to carry out reactions. They are also indispensable for signal transduction and cell regulation, often via kinases and phosphatases. They also generate movement, with myosin hydrolyzing ATP to generate muscle contraction, and also transport cargo around the cell as part of the cytoskeleton. Other ATPases in the cell membrane are ion pumps involved in active transport.
 
        
             
        
        
        
Para mi opinión creo que es la repuesta correcta el encéfalo consta de 3 parte el “cerebro, cerebelo y bulbo raquídeo” respuesta