The board turned down his request for a loan. As used here, turned down means: A reduced, B rejected, C delayed, D folded.
- The object is a request, and a request can be granted or refused.
- D takes turn literally, and nothing in the sentence is being folded.
- Turn down can mean to lower the volume or heat, but a request is not a sound or a flame, so A does not fit.
- Replace it with one verb: the board rejected his request. The sentence keeps its sense.
Answer: B, rejected.