Answer: Utilice los cruces peatonales.
Explanation: Ok, the exercise is:
"Escoge el mandato que aplica a la siguiente situación: Estás en la ciudad y quieres cruzar la calle."
This can be translated to:
"Choose the thing you need to do in the next situation: You are in the city and you want to cross the street"
The options are:
a) Utilice los cruces peatonales. (Use crosswalks.)
b) No pise la grama (Do not step on the grass)
c) Ceda el paso. (Yield.)
Of course for the way this is written, in this situation you are a pedestrian that wants to cross the street so the correct thing you must do is use the crosswalks, then the correct option is a.