"al" would correctly complete the sentence because it correctly links the verb "vamos" to "parque"
-Let's go to the park at five in the afternoon.
Escucho?
what is the question?
The answer is escucha.
The subject here is Marta, and we have to conjugate the verb to match the subject, which is a 'she' and you just add 'a' to the stem.
Answer: Falso
Explanation: Hemos and recorrido are a few examples.