All efforts of cloning an animal will be if there is not enough diversity in the group to overe illness.
A. in need
B. in place
C. in vain
D. in case
网友回答
A. in need
B. in place
(答案→)C. in vain
D. in case
解析：词义辨析。A需要；B在合适的地方；C徒劳；D以防万一；结合句意可知C正确。句意：如果没有足够的多样性来克服疾病，所有克隆动物的努力都是徒劳的。