A Frenchman who lost his arms and legs successfully swam across the Channel, a challenge he _____

for two years. [ ]

A. has been preparing

B. had been preparing

C. has prepared

D. prepares

就给定资料所反映的主要问题，用1 300字左右的篇幅，自选角度，自拟标题进行论述。要求中心明确，内容充实，论述深刻，有说服力。