Why is here the answer "wouldn't"?

[Semeo]

English Language Tests, Intermediate level

ESL/EFL Test #120 "Conditional Tenses", question 6

If he hadn't been driving so fast, he ......... have hit the motorcyclist.

(a) didn't
(b) hadn't
(c) wouldn't
(d) hasn't

English Language Tests, Intermediate level

ESL/EFL Test #120 "Conditional Tenses", answer 6

If he hadn't been driving so fast, he wouldn't have hit the motorcyclist.

Correct answer: (c) wouldn't
_________________________

I need the answer next to the quetion please.
And why is here the answer "wouldn't" but not "hasn't"?

Semeo

[Yankee]

When you finish the test and click on "Check your score", you can find the correct answer in the sentence and also under the sentence.

For this sentence the correct answer is: (c) wouldn't.

[Yankee]

Hi Semeo

I see that a second question, a title and your name have been added since you first posted.