The instructions in the link say:
The choice of tense depends on whether the speaker is "still inside" the "unit of time" that's being used or implied:
Use the present perfect ("he ido") form when talking about the past:
- today, this week, this month, or this year
Use the indefinido ("fui") form when talking about the past:
- yesterday, last week, last month, or last year (or further back)
But then an example on the lesson page has this:
Ellos han visto el amanecer.
They saw the sunrise.
In this sentence, as with many of the quizzes, there is no way to know the context and so we have to follow the instructions as to which tense to use. Part of the fun of the quizzes is not reading the directions.
I think this is the root of the frustration here. Perhaps if more context were provided we could have a chance of answering without the addition direction needed.