Answer:
Subject B.
Explanation:
It is given that,
There are total four subjects, namely A, B, C and D.
Out of these four subjects, we have, Subject B wants to impress the researcher above everyone while the other subjects do not care.
Since, Subject B wants to impress the researcher, they would want to use any means as possible so that the researcher gets amazed by them.
For this, it is highly possible that they will start answering questions in a way that makes them impressive, which would lead them to not answer questions honestly.
While the other subjects do not care whether the researcher is impressed, this will make them give the answer honestly.
Hence, Subject B is least likely to answer the questions honestly.