In contrast to the prevailing theory that the universe is static, Edwin Hubble's ___________ astronomer Vesto Slipher.
Which choice completes the text so that it conforms to the conventions of Standard English?
observation: that galaxies are moving away from us was first noted by the
observation; that galaxies are moving away from us was first noted by the
observation, that galaxies are moving away from us was first noted by the
observation, that galaxies are moving away from us was first noted by: the
Correct Answer: A
Choice A is the best answer. The colon introduces the content of the observation ("that galaxies...").
Choice B is incorrect because a semicolon separates independent clauses. Choice C is incorrect because the comma is too weak or unnecessary. Choice D is incorrect because the colon is misplaced.