Which of the following is a clause?

A clause is a group of words that contains a subject and a verb and expresses a complete thought, or it may be dependent and require additional information to complete its meaning. The correct choice, which states "Although she cannot be there on Monday," is indeed a clause because it includes a subject ("she") and a verb ("cannot be"). The word "Although" introduces a dependent clause, providing a condition that adds meaning but does not stand alone as a complete thought.

The other options lack this essential characteristic of a clause. The first choice, "After several meetings about the situation," is a phrase that begins with a preposition and lacks both subject and verb. Similarly, "In addition to his academic record" is a prepositional phrase that describes an addition but does not contain a subject or verb. Lastly, "The next speaker on the agenda" serves as a noun phrase that identifies a specific person but, again, does not include a verb or express a complete thought. Understanding the structure of clauses is crucial in identifying them correctly in English grammar.