I’d choose A: Enrolling in a course guarantees that you will receive college credit for it as the answer.
The reason why this might be incorrect is because of the word guarantee. You are not guaranteed to get college credit. You will potentially earn college credit if you have work harder for them. It’s a dream for many students to earn a college credit while still in high school. The biggest benefit, however, of dual enrollment is that you will start accumulating college credit earlier in advance and this will help you graduate on time or even early.