Identify the sentence that is not a run-on

a)Some people are real risk-takers; my cousin loves sky diving.
b)My cousin loves sky diving yes some people are real risk-takers.
c)Some people are real risk-takers my cousin loves sky diving.
d)Some people are real risk-takers for example my cousin loves sky diving.

I think it is a but i am not sure.

You're right. A is not a run-on.