On Monday when you asked your friend if you should dump the person you're dating, she said yes. Now on Wednesday, she says no. Since you asked her twice and got two different answers, in terms of validity and reliability, her advice is not ___.

Reliable

Explanation:

From the example, when a friend was asked about a decision you are about to take, the first answer that was said to you on Monday was quite different from the answer that was also said to you on Wednesday.

In respective of the final decision to be made by you, the answers that were provided by your friend was not reliable. because a clear advice was not provided.