What situation is the best example of opportunity cost?

For example, choosing public transportation to travel to a particular destination by foregoing the option of traveling in one’s own car is a good example of opportunity cost, because you end up saving money which needs to be spent on fuel. You can read about the Indian Economy Notes For UPSC Preparation in the given link.

Further readings:

1. Bad Banks – Idea Proposed Due to COVID-19
2. Cashless Economy in India – UPSC GS-III Notes