Is there a required minimum distribution for a 401a pension plan? I wasn't notified of any specific RMD and I can't answer the interview properly.

I have a tax free state pension plan which is a 401(a) plan.  I receive monthly payments.  I wasn't notified of any specific RMD, but now that I am 70 1/2 the interview is asking me how much of my distribution is required.  How do I answer?