Question

the ______ was once used to measure the blueness of the sky) is now obsolete.
which choice completes the text so that it conforms to the conventions of standard english?
choose 1 answer:
a cyanometer, which
b cyanometer—which
c cyanometer (which
d cyanometer which

Explanation:

To determine the correct answer, we analyze the punctuation and sentence structure. The phrase "was once used to measure the blueness of the sky" is a non - restrictive clause (it provides additional information about the cyanometer but is not essential to the main meaning of the sentence). For non - restrictive clauses, we use parentheses to set off the clause in this context (since the original sentence has a closing parenthesis at the end of the clause). Option A uses a comma, which is not appropriate here as it would not match the closing parenthesis. Option B uses a dash, which is also incorrect for this structure. Option D lacks appropriate punctuation to set off the non - restrictive clause. Option C uses parentheses to introduce the non - restrictive clause, which is consistent with the closing parenthesis in the sentence.

Answer:

C. cyanometer (which