Out of these choices, which is the most formal?
a) you've gotta do this stuff now, tho.
b) you really need to get 'er done.
c) you have to do this- no lie.
d) you truly need to accomplish this task.

type of error:

the error in the sentence is a "dangling modifier". a dangling modifier is a phrase, word or clause that "dangles" because there is not target to modify. in this case, "after mopping the floor" is the dangling modifier since it has no word to modify. the noun "house" cannot mop the floor; therefore there is a mistake in the writing of the sentence.

eli whitney was an american inventor best known for inventing the cotton gin. this was one of the key inventions of the industrial revolution and shaped the economy of the antebellum south.