I think the answer would be B.
Clothing differed between time periods, transportation is very useful in distinguishing between time periods (ex. riding on horses vs in a limousine). And setting can help, because describing a modern city with lots of structures would indicate you are talking about a more recent time period.
Font isn’t really helpful, the only way I could think it would be useful is that cursive is not really used in modern writing, however since it was used for so long it would not help when distinguishing between time periods in the past.