I think the answer would be B but that could be wrong. I hope this helped!!
Answer:
in the wall of the right atrium of the heart.
Explanation:
The sinoatrial node (SA), consisting of spindle-shaped cells, initiates the electrical activity of the heart. From its location in the right atrium in proximity to the superior vena cava, the electrical activity spreads to the atria, whose cells are larger than those of the SA.
The answer to this question is D
A nucleophilic addition-elimination reaction between the carboxylic group and the amino group bonds the amino acids together.