The sentence where "fui" means "I was" is: "Fui estudiante."
In the given options, the sentence "Fui al médico" is the correct answer where "fui" means "I was." To determine this, you need to understand the verb "fui" and its meaning in Spanish. "Fui" is the past tense of the verb "ir," which means "to go." In this sentence, "fui" is used with the preposition "a" to indicate going to a specific place, which is "al médico" meaning "to the doctor." So, "Fui al médico" translates to "I went to the doctor," where "fui" means "I was" in the past tense.
