How can I know which meaning of the three meanings of present perfect is the one intended by the writer?especially when there is no time marker and it is a mere sentence within exercise not full text.
"I have eaten my breakfast"
Did he mean that : this happened from minutes-just happened-
Did he mean that: the result of this not the action itself.
Did he mean that: he started eaten in past and still eating until time of speaking
The most likely meaning is that the person has eaten and doesn't want any more to eat. The time is unclear without the context, but it's still recent enough to affect their appetite now. I would say the third of your options doesn't work here.