The audience for whom a piece is being written will determine the language used and the style.
Whom should be used to refer to the object of a verb or preposition. When in doubt, try this simple trick.
If you can replace the word with he or she, use who. If you can replace it with him or her, use whom.
Who should be used to refer to the subject of a sentence. And whom is used in formal or written English instead of who when it is the object of a verb or preposition when you ask about the name or identity of a person or group of people.
Whom vs who at the beginning of a sentence. Technically, that whom is correct because it’s the object of the verb, called yet almost no one would say it that way.
It means that, when the pronoun’s at the beginning of a sentence, even the most formal writing can use who as an object.