Pick the correct sentence that should follow the given sentence: The milkman is at the door. 

Pronouns are words utilised in place of nouns. They can only be used once the noun is used or mentioned. Pronouns are of several types, such as personal, reflexive, emphasising, relative, demonstrative, indefinite, interrogative, and possessive. Personal pronouns take three persons: first, second, and third. Personal pronouns can also be either singular or plural. Here, the milkman is the third person, who is being spoken about, and thus, he takes the singular pronoun “he.” The speaker is inside, speaking to their companion. Since there is more than one person inside, the speaker takes the first person plural pronoun “we.” So, the correct way to frame the sentence is, “The milkman is at the door. He wants to know if we want milk.”