Final answer:
The correct verb form in this sentence is 'quiera'.
Step-by-step explanation:
The correct verb form in this sentence is 'quiera'. The phrase 'Busco una pareja que' indicates that we are looking for someone who wants to (querer) do something. In this case, the desired action is 'reservar último sábado de julio'. Since 'querer' is an irregular verb, it changes to 'quiera' in the subjunctive mood. So, the correct form of the verb is 'quiera'.
Learn more about Spanish verb conjugation