The Rotation Rate of the Planet Venus Was First Determined

Multiple Choice

The rotation rate of the planet Venus was first determined by measuring:

A) the time delay of radio pulses after reflection from the planet's surface.
B) the Doppler shift in radio waves reflected from the planet's surface.
C) photography from the Hubble Space Telescope at infrared wavelengths that penetrate the planet's clouds.
D) sequential photography of Venus from Earth.