Answer:
The sentence that contains a dangling modifier is To raise a good dog, persistence is important.
Explanation:
A dangling modifier or a misplaced modifier is a word that is supposed to modify a word but because of its incorrect collocation in the sentences, it makes the general meaning confusing. The sentence To raise a good dog, persistence is important, needs to be modified in order to convey a clear message, since after the words To raise a good dog -which is the modifier-a noun is expected.