I think it is option 3 which is yo.
The trip of Charlie and Sophie ______ in Mexico.
Answer:
Nueve mil cien
Explanation:
Diez mil − novecientos = 10,000 - 900 =9,100
= Nueve mil cien
Sr. Rivear, since he is a Señor, you would address him as Ud. (Usted)
