Which of the Following Sentences Is Combined Correctly

Multiple Choice

Which of the following sentences is combined correctly?

A) Exchange your email address with someone who sits near you, you can find out the homework if you have to be absent.
B) Exchange your email address with someone who sits near you, then you can find out the homework if you have to be absent.
C) Exchange your email address with someone who sits near you, if you can find out the homework if you have to be absent.
D) Exchange your email address with someone who sits near you, so you can find out the homework if you have to be absent.