What central idea is implied in this paragraph?
Elizabeth Van Lew did not follow the rules society set
forth for ladies of her time and social class.
Elizabeth Van Lew was a successful spy because
society did not expect a lady to serve in that role.
Elizabeth Van Lew was able to disguise her spying
activities because she kept her views about the war to
herself.
Elizabeth Van Lew created for herself an untrue but
believable cover story: she was a wealthy lady living in a
fancy neighborhood.

Elizabeth Van Lew was a successful spy because society did not expect a lady to serve in that role.

Explanation:

According to a different source, this is the paragraph the question refers to:

It may seem surprising that no Confederate sympathizers took action against Van Lew, given her strong and public views on secession and slavery. Surely there were suspicions, especially among her upper-crust neighbors, but the matter never went beyond those suspicions. Historians have suggested that the secessionists were victims of their own cultural bias, believing that no aristocratic person, and certainly not a lady, would ever consider taking part in anything as impolite as spying. A true lady managed her servants, prepared parties and gatherings, and blindly supported her husband. Such attitudes worked in Van Lew's favor, diverting suspicion from her.

In this paragraph, we learn of the way in which people tended to think about ladies, and in particular, aristocratic ladies. We learn that most people did not believe that polite ladies of society would be capable of becoming involved in something like spying. This appeared to be a contradiction that was unimaginable. Because of this, no one suspected Elizabeth Van Lew, allowing her to do a better job as a spy.

i believe the answer is b. we