The correct answer would be letter C.
        
             
        
        
        
Type of chocolate bar, size of it, surface it is placed on, etc
Controlled variables are anything that stay the same for both trials
        
                    
             
        
        
        
There is a valve at the meeting point between each ureter and the bladder prevents the back flow of urine from the urinary bladder to the kidney
        
             
        
        
        
Most enzymes fall into the protein category
        
             
        
        
        
Answer:
tRNA molecules bring a specific amino acid to the ribosome, according to the mRNA codon.
Explanation:
In the context of protein synthesis, an mRNA molecule contains the specific codons that encode the amino acids that will be part of the protein. The tRNA is in charge of bringing the amino acids to the ribosome, according to the specific information of the mRNA codons.