My guess is that you are flustered and just drawing a blank. My usual when that happens is to go take a shower and wash my hair. For some reason that relaxes enough that it comes back as an 'aha!'. Playing through the shop in your mind may help. What came before and after the answer may help. An incomplete shop in most cases will not submit. Are there any choices or options for the answer or is it free form? If you look over the instructions again for that part, does it jog your memory?
Rarely have I heard of a shopper terminated because their first shop was rejected. If you fail to report the shop, that is a different issue. So do try to at least submit the report. If you absolutely cannot come up with the missing information before the deadline for submission, acknowledge that you asked but have forgotten the response and offer to get back to them by email when you remember it.