What is the central idea of "stopping by woods on a snowy evening"?
a: without alerting the neighbor, a man stops in his neighbor’s woods outside the village
b: while on a long journey to take care of business, a man stops by snowy woods to give his horse a rest
c: a man stops by dark woods in the middle of nowhere to watch the snow fall
d: a man stops to admire woods on a snowy evening but must leave because he has things to do