|Question 19Verbal

Source Texts

Text
In the Silurian hypothesis, astrophysicist Adam Frank and climatologist Gavin Schmidt suggest the geological record may contain evidence of prehuman advanced civilizations. This sensational hypothesis obscures the scientists' practical        Frank and Schmidt don't believe such a civilization existed, and their "hypothesis" is a thought experiment exploring the traces our own civilization will leave in the geological record.
Which choice completes the text so that it conforms to the conventions of Standard English?
aim, however:
A
aim, however;
B
aim however,
C
aim however:
D