Answer:
Astronomers often develop their ideas <u>D) in a team</u>
Explanation:
A collective noun is a noun that is normally in its singular form but that refers to more than one person, animal, thing or concept considered as a single entity. The word “team,” is an example of collective noun because it is singular but it refers to a group or two or more people or animals. Other examples are <em>congregation, class, herd, flock, gang, mob, group, and family.</em>
Option D, then, is the correct answer because it completes the sentence with a collective noun.