**Concept: The question tests on the area of Probability**

**Solution:**

We are not selecting a married couple. We are selecting a married employee from B and thus the probability of such an event is 50/500 =1/10

There will be only 1 partner of the married person in A and the probability of that event is 1/400

This is an AND event(1 married person from A and the partner in B)

=> 50/500* 1/400 =1/4000

**(option c)**