Final answer:
The correct verb conjugation in the present tense for 'querer' is 'quiero'.
Step-by-step explanation:
The correct verb conjugation in the present tense for the sentence 'Yo (querer) mucho a mi amigo Juan y mi hermana Estela' is quiero. 'Quiero' is the first-person singular form of the verb 'querer' in the present tense.
Learn more about Verb conjugation in the present tense