SAT OwlResearchers have identified one reason that ancient Roman marine concrete has lasted so long______ when seawater seeps into the concrete, it reacts with volcanic ash in the mixture to form new minerals that strengthen the material.
Which choice completes the text so that it conforms to the conventions of Standard English?
:
,
(no punctuation)
; and
Show answer and explanation
Answer: A
The first part is an independent clause that announces "one reason," and the second part is an independent clause that explains what that reason is. A colon correctly introduces an explanation after a complete clause. A comma would create a comma splice.
Choice B creates a comma splice, because the text after the blank is a full independent clause.
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