The best choice to describe Rainsford's motivations or values in this interaction is:
B. Rainsford's sense of honor is so strong that he refuses a deal that would help him.
This response highlights Rainsford's strong principles and moral code. He is unwilling to accept a deal that requires him to remain silent about the horrific nature of Zaroff's hunting practices, even if it would potentially save his life. This indicates that Rainsford values integrity and honor over simply preserving his own safety.