It seems that ________ is no set amount of time that everyone needs to sleep each night.

• A. that
• B. this
• C. there
• D. these

Answer: (C)

The idea being tested is how to introduce existence in a sentence after “It seems that.” In English, to say that something exists or doesn’t exist, we use the existential form there is/there are. Here you want to convey that there isn’t a fixed amount of sleep for everyone, so the natural, correct construction is there is no set amount of time that everyone needs to sleep each night. The word there acts as a dummy subject to start the clause, and is followed by is to link to the description “no set amount of time.” The relative clause that everyone needs to sleep each night then describes what kind of amount you’re talking about. Using this/these wouldn’t introduce the existential idea properly, and that would disrupt the natural grammar of the sentence.