To Measure How Dense a Planet Is (To Know Whether

Multiple Choice

To measure how dense a planet is (to know whether it is made of rock or gas and liquid) they must be able to measure the planet's mass from the Doppler shift and

A) the planet's temperature from its spectrum
B) the planet's velocity (speed) toward or away from us
C) the planet's radius using the transit method
D) the planet's color from photographs
E) whether the planet has rings around it or not