Which sentence has an error using a commonly confused word?
sundays too, my father got up early.
the little boy ate too poptarts for breakfast.
if you work too hard, then you'll never have any fun.
marsha couldn't decide whether she'd been too harsh or not.

B. The little boy ate too poptarts for breakfast

Explanation:

The word too is used as an adverb. It's the same as if you were to say words like: also, additionally, very, or extremely. These words are often confused, because they are homophones: they sound alike but have different meanings. The proper spelling that you would use, is the word two, because it's the numerical spelling.

the correct answer would be:  

a. adverb phrase