What answer does NOT correct this run-on sentence?

If you want to take the car, just ask mom i'm sure she will let you.

A. If you want to take the car, just ask mom; i'm sure she will let you.

B. If you want to take the car, just ask mom. i'm sure she will let you.

C. If you want to take the car, just ask mom, i'm sure she will let you.

D Ask mom if you want to take the car. i'm sure she will let you.

C. If you want to take the car, just ask mom, I'm sure she will let you.

Explanation:

To correct a run-on sentence you must use either a coordinating conjuction or a proper punctuation, such as a period or a semicolon, to separate the two complete sentences.

A comma is not a proper punctuation to separate two complete sentences.

Here one sentence is "If you want to take the car, just ask mom". The other sentence is "I'm sure she will let you". You cannot use a comma to separate them. Thus, the option C. If you want to take the car, just ask mom, I'm sure she will let you", is incorrect.

Option A uses a semicolon, thus it is correct. Option B uses a period, thus it is correct. Option C changes the sentence, but it is grammatically correct.