Which words most contribute to the tone of regret in Robert Frost’s "The Road Not Taken"?

The map shows the allied strategy in the pacific. what does the movement of allied troops reveal about their strategy? the allies’ objective was to reach japan as soon as possible. the allies kept getting diverted in their quest to reach japan. the allies overtook outlying islands to make access to japan easier. the allies retreated just before they reached the first set of islands.