Select the most appropriate option to fill in the blank: I cannot interview…

Answer: unless

Complete sentence: I cannot interview these candidates unless I know their academic background.

• Why this is correct: "unless" introduces a negative condition meaning "except if." The sentence therefore means you will interview the candidates only if you know their academic background.

• Why the other choices are incorrect:

  1. "if" would reverse the meaning: it would say you cannot interview them when you do know their background, which is the opposite of the intended idea.

  2. "because" gives a reason rather than a condition and would imply knowing the background prevents interviewing, which is illogical here.

  3. "so that" expresses purpose (in order that) and does not create the conditional exception needed in this sentence.

Tip: Use "unless" when you want to express "except if" or a negative condition that must be met for something to happen.