a. Pranjol thought that tea is very popular because almost everyone in their train compartment was drinking tea. The fact that tea was being consumed by a majority of people around them indicated its widespread popularity. Additionally, Rajvir mentioned that over eighty crore (800 million) cups of tea are consumed daily worldwide, which further emphasized the popularity and global reach of tea as a beverage. b. They were on a train at the time when the vendor called out and offered them tea. The vendor's high-pitched voice and the interaction through the window imply that they were travelling on a train compartment, possibly during a stop. c. After sipping the tea, Pranjol got busy engrossed in his detective book, while Rajvir continued to enjoy the scenic views outside the train.