Why might the author have capitalized the word "DO"

Which element forms the basis of all organic organisms a carbon b oxygen c hydrogen d nitrogen

This is a scaffolding of protein fibers that us sell keep it shape in a cell division and cell movement

16 select the correct answer from each drop-down menu. sharks, whales, and dolphins share similar features such as body shape and the position of fins. hoy while whales and dolphins have lungs. these differences indicate that the organisms share a comme whales also possess a vestigial pelvic bone. the presence of the pelvis bone may indicate that whales reset next