Final answer:
The verb 'tengo' best completes the sentence 'Yo ____ catorce años'.
Step-by-step explanation:
The verb that best completes the sentence 'Yo ____ catorce años' is tengo. Tengo is the first person singular present tense form of the verb 'tener', which means 'to have'.
Learn more about Completing sentences with the appropriate verb conjugation in Spanish