<em>The answer would be: </em>
C. ¿Ibas a la playa de niño?
Answer:
El jugo es la más dulce de las dos bebidas.
Explanation:
I think the problem with the other answer is that the object (la) is referring to bebidas, which is femenino, so it should be la instead of el.
The correct answer would be: Cuando _X_ lavo el coche, no uso detergente.
Good luck!