Which choice completes the text so that it conforms to the conventions of Standard English?
A
decade: while
B
decade. While
C
decade; while
D
decade, while
Explanation
Correct answer: D.
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.
Why the other choices are wrong
Choice A
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
Choice B is incorrect because it results in a rhetorically unacceptable sentence fragment beginning with "while."
Choice C
Choice C is incorrect because a semicolon can’t be used in this way to join a main clause and a subordinate clause.