This is used in organic compounds as key components in the DNA molecule and ATP

a. nitrogen

b. oxygen

c. carbon

d. phosphorus

Carbon is what is used

Phosphorus is a key component of both ATP and DNA because of their phosphate groups. DNA has one phosphate group with four molecules of phosphorus each per nucleotide. ATP is made up of three phosphate groups with four molecules of phosphorus per each group. While carbon is a good answer, the best answer that specifically pertains to both DNA and ATP is phosphorus.