What was your answer? You'd have to bomb this question pretty badly for it to sink an interview.
I'd guess that you didn't get the job for some other reason, which could be in your control or not. You could have had a poor technical showing that day. You might have been so awesome they thought you'd seen all the questions before. The interviewers could have been having a bad day. They might have had multiple candidates and had to pick one. They might have suddenly instituted a hiring freeze. You might have seemed like a poor cultural fit. They might have been racist. The hiring manager might have left the company suddenly and they decided to close the req. There are at least a hundred reasons you might not get a job and you generally have no visibility into the real reason.