AMC 10B 2008 Problem 21

Ten chairs are evenly spaced around a round table and numbered clockwise from 1 through 10. Five married couples are to sit in the chairs with men and women alternating, and no one is to sit either next to or directly across from his or her spouse. How many seating arrangements are possible?

Answer Choices
A. 240
B. 360
C. 480
D. 540
E. 720