Question

Fill in the blank with the most appropriate word.
"_________ is your phone number?"
"It's $2229$".

• A. Where
• B. How
• C. What
• D. Who

Answer 1

Answer: (C)

What

Here, 'what' as an interrogative adverb is correct because it is used in questions to ask for particular information about somebody/something. Here, the information being asked is the phone number.
'Where' as an adverb is used to imply in or to what place or situation.
'How' as an adverb is incorrect as it implies in what way or manner.
'Who' as a pronoun is incorrect as it is used in questions to ask about the name, identity or function of one or more people.