题目选项分析

Biologist: Species with broad geographic ranges probably tend to endure longer than species with narrow ranges. The broader a species' range, the more likely that species is to survive the extinction of populations in a few areas. Therefore, it is likely that the proportion of species with broad ranges tends to gradually increase with time.

The biologist's conclusion follows logically from the above if which of the following is assumed?

【选项】There are now more species with broad geographic ranges than with narrow geographic ranges.