Given the task definition and input, reply with output. Given a prompt and four completions, select the completion that is the most plausible in continuing or answering the prompt. This task is designed to test common sense and has various categories ranging between idioms, negated statements, polysemy, subject referencing, and quantitative reasoning. Generate either Completion A, Completion B, Completion C, or Completion D.

Prompt: John, a runner, had always avoided cigarettes
Completion A: because brain cancer is life-threatening.
Completion B: because John was afraid of putting things in his mouth.
Completion C: because cigarettes can be expensive.
Completion D: because he wanted to remain in peak physical condition.
Completion D