What is a too narrow subject

Explanation:

It is one where the subject is not expanded enough. Its scope is just not large enough to be of any interest.

When you are asked to write something about a coke bottle (which is pretty narrow itself) and write about why the glass bottle has to be made at a certain temperature and you spend 3 pages doing it, the subject is a little narrow. Your teacher is going to throw up her arms and say after you declare for the 58th fact about why the environment temperature must be controlled to 0.001 of a degree, that your subject is too narrow for the assignment.

Never make your teacher become so frustrated that she utters a "who cares?" under her breath.

If you are a male, listening to a discussion on cosmetic brushes is too narrow a subject.

a is is the correct answer