Answer: B. Parallelism.
Step-by-step explanation: parallelism is a literary device that consists in the repetition of a grammatical structure of words or phrases in order to maintain the symmetry in the text and to produce a more strong effect. The given line is a clear example of parallelism because of the use of similar grammatical structures in both parts of the sentence "The more men have to lose" and "the less willing are they to venture."