What characteristics differentiate troposphere from other layers of atmosphere?
I. It is where most water vapor is found.
II. It begins about 16km above the Earth's surface.
III. It is where all weather phenomena virtually take place.
IV. It is where temperature decreases with altitude at 2*C/1000ft.

a. I and III only
b. I, Ii and III
c. II and III only
d. I, II, III and IV