Televisions and video players have gold components inside, and it is even used in the instruments ________ enable astronauts to travel...

Televisions and video players have gold components inside, and it is even used in the instruments ________ enable astronauts to travel...

• A. That
• B. Which
• C. Who
• D. Where

Answer: (A)

The idea being tested is how to use a relative pronoun to introduce a defining (restrictive) clause about things. Here, the word that fits best because it specifies which instruments are being talked about: the ones that have the ability to enable astronauts to travel. When the clause is essential to identify the noun, we use that (for things) without a comma. Using which would typically introduce extra, non-essential information (often set off by commas), and who is for people, not things, while where is for places. The subject instruments is plural, so the verb matches with enable. So the natural, correct construction is the instruments that enable astronauts to travel.

The idea being tested is how to use a relative pronoun to introduce a defining (restrictive) clause about things. Here, the word that fits best because it specifies which instruments are being talked about: the ones that have the ability to enable astronauts to travel. When the clause is essential to identify the noun, we use that (for things) without a comma. Using which would typically introduce extra, non-essential information (often set off by commas), and who is for people, not things, while where is for places. The subject instruments is plural, so the verb matches with enable. So the natural, correct construction is the instruments that enable astronauts to travel.