What had the individual been doing before the bus arrived?

The individual had been waiting before the bus arrived reflects a common scenario where one would wait for public transport. This answer indicates the action that naturally precedes the arrival of a bus, as people typically arrive at a bus stop in advance of their departure rather than engage in other activities. This context implies that waiting is a necessary activity that ensures the individual is present for the bus when it arrives. In contrast, the other options suggest actions that might keep someone occupied, making it less likely for them to be immediately ready for the bus's arrival. Therefore, the focus on waiting aligns perfectly with the sequence of events related to public transportation.