Keep getting this question in interview, what am I supposed to say?

I keep getting this question when interviewing for grocery stores: "A coworker is struggling. You've already repeatedly assisted them and trained them on how to do their work, but they just can't get the hang of it. You also need to make sure you meet your own production goals. What do you do?" I just keep saying that I'd help my coworker only insofar as it wouldn't sabotage what I'm doing, and I explain my reasoning as, "It's better to have one person at 100% and one person not at 100% than two people both not at 100%." Interviewers seem mostly satisfied with this response, but is it actually a little cold/calculating and therefore preventing me from advancing in the interview process? Should I just tell them "I just help my coworker because it's the right thing to do, teamwork, solidarity, rahhhh, etc."? Alternatively, is this question totally subjective and just a vibe check?