Answer:
The best option is A) Topic sentences.
Explanation:
A topic sentence has the purpose of informing readers on what the paragraph is about. It works as a map of the paragraph, letting readers know where the author is going and how he/she is getting there in terms of the idea being developed. The sentences that come after the topic sentence function as its support, as evidence to defend the topic.
In the excerpt we are studying here, "As a member of the crisis management team, you are required to attend our biannual crisis management workshops" functions as a topic sentence. The purpose of this paragraph is to inform the reader that he/she needs to attend a certain event, and that the reason for that is his/her being part of a certain team. The rest of the paragraph merely offers additional information, support for the topic sentence - where and when the event will be, and where the reader can find registration information.