"How will your performance in your worst class affect your performance on this job?"
This question is another opportunity to show many good traits. You can display traits such as endurance, effort, and willingness to work on things you don't like. This is very important because during your career, you will have to do many boring things. This long answer will display that you are a person that will do good at any task.
Short Answers
"No matter if I liked the class or not, I always tried my hardest. As a result, the lowest grade I ever received was a B. So I'm confident that I'll be good at any task."
"I had one class where I really struggled. I asked more questions and studied more. As a result, I did very well. So even if I'm struggling, I feel I can find ways to do a good job by putting in more effort."
"My performance in my worst class will positively impact my performance on this job. I struggled with a logic class, but I studied harder, researched more information, and I never gave up."
Long Answers
"I remember I did terrible in my astrology class. I didn't have much interest in the subject and I really didn't know that I would struggle in it. I thought about just doing enough to make it through, but I decided that I was going to put some effort into it. I continually asked questions and studied more for this class than I did in others. I got a B for all my effort, but at least I didn't give up and I kept pushing forward. So now I know that whether I like a project or not, I'll do the best I can because it's my responsibility."
This answer shows maturity and the interviewer should like it.