Answer: The farmer chooses errands on a rainy day, because a sunny day would be for planting and tending the land. The farmer could go and run errands on a sunny day, but his crops would not be tended for the day.
The business man would choose to work on a rainy day, because his new suit can't get wet. He is choosing to stay inside and protect his new suit, and giving up the opportunity to run errands.
Hope it helps!
