Select the option that can be used as a one-word substitute for the given group of words.

One who supervises in an examination hall

Invigilator

The one-word substitute for "one who supervises in an examination hall" is invigilator.

• Verifier means someone who checks or examines something to make sure that it is correct or genuine.
• Inspector means someone who officially examines something, especially to ensure that it complies with the law or regulations.
• Manager means someone who is in charge of a particular area of work or activity.

Invigilator means someone who supervises an examination or test to ensure that it is conducted fairly and that no cheating occurs. It is the most appropriate word for the given group of words because it specifically refers to the supervision of examinations.