Which of the following pronouns correctly completes the sentence: If Madelyn doesn't arrive quickly, ____ will not be able to go to the concert with us?

The sentence "If Madelyn doesn't arrive quickly, ____ will not be able to go to the concert with us" requires a subject pronoun to properly complete it. The context of the sentence indicates that Madelyn is the one who may or may not arrive, and if she does not, she will be the one unable to go to the concert.

Using "she" correctly identifies Madelyn as the subject of the latter part of the sentence where it discusses her ability to attend the concert. Subject pronouns like "she" are used when the pronoun performs the action of the verb in the sentence, which is fitting here since it is Madelyn who would not be able to go if she does not arrive.

Other choices are not suitable in this context. "We" would imply a collective group, not focused on Madelyn specifically. "Her" serves as an object pronoun meant for direct or indirect objects, which does not align with the subject role needed in this sentence. "They" introduces confusion, as it refers to a different subject and does not maintain the focus on Madelyn. Therefore, "she" is the most logical and grammatically correct choice for completing the sentence accurately.