It would be fui. The answer is C
1) Nosotros somos muy delgados.
Answer:
1. Te escribo.
2. Vengo.
3. Leo.
4. Creo OR pienso.
5. Entiende OR comprende.
6. Lee.
7. Compartimos
8. Hacemos ejercicio OR salimos a hacer ejercicio OR salimos a correr.
9. Vamos.
10. Vivimos.
11. ¿Tú tienes mucho trabajo?
Explanation: Just to elaborate a little on the answer, it can be added that the passage is a letter that a student is writing to his friend Ángel from the library. He goes to the library everyday and reads a good book, and he believes ("creo") or thinks ("pienso") that it is important to read just for fun (or out of pleasure). His roommate does not understand why he likes reading. He only reads textbooks. But, nevertheless, they share some (common) interests. They are both athletic; they exercise, or go out to exercise, or go for a run, in the mornings. They also like science; they go to their biology class in the afternoon. They live in an apartment that is located near the lab. And he concludes by asking his friend "And you, how are you? Do you have a lot of work?" (or "Are you busy at work?").
