Answer:
Tossing two coins once.
Explanation:
According to the diagram, there are just two outcomes: either H or T.
The spinner has three outcomes, and the cubes have 6 outcomes each, so we can eliminate the top two options.
If the person were just tossing one coin, the outcomes would be H or T, but there are more outcomes than that, so the diagram represents tossing two coins once.
Hope this helps!