Consider the situation where you've applied for a technical position (i.e. in Software Engineering) and on a phone interview you were asked a technical question. Regardless of the reason, you respond to the question with either an "I don't know" or an answer that isn't what the interviewer was trying to discern in regards to your personal expertise.

After finishing the interview, you realize the correct answer. What should you do?

Let your response rest as it is or should you respond, via email, explaining why you initially gave an incorrect answer and provide an amended response?