Based on the passage above, the best synonym for reasonably seems to be:
D. sensibly
Explanation:
The narrator of the excerpt says the people who were waiting for the train were also drinking. Then he says they were "waiting reasonably for the train." What he means here is that people found an intelligent way to wait for the train's arrival. Instead of simply standing at the platform, doing nothing, they found a sensible manner to spend their time.
For that reason, the best synonym for "reasonably" seems to be "sensibly". As a matter of fact, both adverbs can generally indicate similar meanings. "Reasonably" refers to an action done with good reason. "Sensibly" refers to an action done with good sense or in an intelligent, reasonable way.
