In discussing Earth orbits, what does retrograde mean? Give an example of a useful type of Earth orbit that is retrograde.

a) Orbiting in the opposite direction of Earth's rotation; Sun-synchronous orbit
b) Orbiting in the same direction as Earth's rotation; Geostationary orbit
c) Orbiting perpendicular to Earth's rotation; Low Earth Orbit (LEO)
d) Orbiting at a fixed distance from Earth; Molniya orbit