When correcting a dangling modifier, what is a good question to ask?
a. what is missing from the sentence?
b. which words are misspelled in the sentence?
c. what is not interesting in the sentence?
d. which words are capitalized in the sentence?

I would probably say A.
A dangling modifier is something that is supposed to be modifying something, but isn't, you could say.
B isn't relevant, because whether or not a word is misspelled has nothing to do with whether or not an adjective is modifying something.
C isn't relevant, because if something is interesting doesn't change the fact that something isn't modifying something else.
D isn't relevant either, because of the same reason, I guess.

I hope this sort of helped! :)