In which sentence is whom used correctly? he is whom you want to speak to. i think he is whom is speaking. whom has the skills to write the essay? i want to know whom wrote the essay.

The correct answer is A. He is whom you want to speak to.

Explanation:

In grammar, both words "who" and "whom" are forms of pronouns; however, they differ in its function. In the case of "who" this is commonly used a subject, but in the case of "whom" this always acts as an object which means it always comes after a verb or after a preposition and can be replaced by the pronoun "him". This means "whom" refers to the person for, about, to whom the action occurs while "who" refers to the agent that carries out an action.

Considering this, the sentence that uses correctly this pronoun is "He is whom you want to speak to" because in this sentence "whom" acts as the object of a verb and can be replaced by the word "him" rather than "he" as "You want to speak to him" and therefore, in this case, it is correct to use "whom", while in other options "whom" has been used as a subject and therefore the correct form is "who".