Answer:
Ustedes han ido al parque.
Step-by-step explanation:
The present perfect, also called antepresente (and also, more broadly, called the perfect past tense) is a perfect tense verbal tense of the indicative mode (although there is also a perfect past tense composed in the subjunctive mode).
The present perfect is used when you want to indicate actions that have been completely completed in a recent time than the current one or the one in which the speaker is located, or when you want to emphasize that temporal proximity.
For example, the sentence "he desayunado cereales" indicates that the action ("desayunar") has taken place today. It would not make sense to use the present perfect if the action had occurred yesterday, or a week ago (in those cases we would say "desayuné cereales", that is, we would use the simple past).