GRE Reading Comprehension: ETS-GRE阅读ETS - 18SDY51L1FFDUDU47

In describing the "evolutionary mechanism", the author mentions which of the following? A. The favorable conditions for nurturing new offspring B. The variable environmental conditions that affect survival of adult snails C. The availability of potential mates for breeding D. The structural identity of offspring to parents of the same hand E. The frequency of unions between snails of different species