Concept:A'isha (RA) is distinguished from the other wives of the Prophet (SAW) by a unique personal circumstance at the time of her marriage.Explanation:A'isha (RA) was the only wife of the Prophet (SAW) who was married to him as a virgin.All his other wives were previously married or widowed.This unique fact is the basis of her distinction mentioned in the question.The other options are incorrect: she was not the oldest, she did not live the longest among all his wives, and she never gave him employment.Answer:B. was married as a virgin