Question

What is the answer to 18?

Answer 1

A period always goes inside the quotation marks. That makes only a and c correct.

Now you have to worry about the capitalization problem. Is it all or is it All?
The rule is if the sentence inside the quotation marks is a complete sentence, then the first letter of the first word is capitalized. In this case, the sentence beginning with all inside the quotation marks should be All.The sentence could stand alone. It  is a complete sentence. The answer should be d.