How Can Astronomers Measure the Composition of an Extrasolar Planet's

Multiple Choice

How can astronomers measure the composition of an extrasolar planet's atmosphere?

A) by measuring the composition of the host star; the planet must have formed from the same initial material
B) by comparing spectra for when the planet is in transit or eclipse with spectra taken at other times
C) by measuring how brightly the planet glows in infrared light
D) by measuring the Doppler shift of the host star