OG详解-OG3 文法 Q18

Choice D is the best answer. The convention being tested is punctuation between a main clause and a subordinate clause. This choice correctly uses a comma to mark the boundary between the main clause (“the colorful…decade”) and the subordinate clause (“while…centuries”) that provides contrasting information about the life span of rougheye rockfish. 
Choice A is incorrect because a colon can’t be used in this way to join a main clause and a subordinate clause. Choice B is incorrect because it results in a rhetorically unacceptable sentence fragment beginning with “while.” Choice C is incorrect because a semicolon can’t be used in this way to join a main clause and a subordinate clause.