Answer: The nucleus.
Explanation: In an atom, there are two main parts, the nucleus and the electron cloud/electron shells. The protons and neutrons are located in the nucleus, and the electrons are located in the electron shells/cloud/whatever.
While both will equate changes in a genetic chain, deletion would have more severe consequences. A substitution mutation usually only causes minor disorders and diseases, like sickle cell anemia. Whereas deletion causes much more serious diseases, like cystic fibrosis, and turner syndrome which is where a female is born with only one X chromosome.
D. Growth. Material forming cells or tissue like cytoplasm.
