How Do Two Unequal Mass Stars Move Around Each Other

Multiple Choice

How do two unequal mass stars move around each other in a binary system?

A) In a common elliptical orbit,always remaining diametrically opposite to each other through one of the foci of the ellipse
B) In straight lines,back and forth past each other
C) In elliptical orbits,about a common "center of mass"
D) The low-mass star moves in a circular orbit around the stationary high-mass star.