The sentence: walking the wire, my dog waited for the squirrel to fall, is an example of split infinitive lack of parallel structure dangling modifier none of these

The answer is: dangling modifier.

Dangling modifiers are separate from the word they modify, resulting in ambiguity, confusion or nonsense. In the example sentence, it is not clear which animal is walking the wire - whether the dog or the squirrel. Supposing the squirrel (which is about to fall) is walking the wire, a correct version of the sentence would be:

My dog waited for the squirrel to fall, which was walking the wire.

to show that social not the correct answer!