Question

which sentence is more formal? peacocks are not born with their colorful tail feathers, but the feathers develop by age three. peacocks arent born with their colorful tail feathers and dont develop them until theyre three years old.

Explanation:

Formal writing typically avoids contractions (like "aren't", "they're") and uses more precise, less colloquial phrasing. The first sentence uses full forms ("are not", "by age three") and a more formal structure, while the second uses contractions and a slightly more casual construction.

Answer:

Peacocks are not born with their colorful tail feathers, but the feathers develop by age three.