What substance in the upper atmosphere blocks ultraviolet radiation from the sun, making life on land possible?
a. methane
b. ozone
c. water vapor
d. carbon dioxide

(B) Ozone

Explanation:

 Ozone is the type of substance which is present in upper atmosphere. The ozone layer is the basically blocks the ultraviolet radiation which is comes from the sun and it is the combination of single molecule with the 3 oxygen atoms.

The ozone layer absorb the ultraviolet radiation and also prevent from the harmful radiation. It helps in make the life possible on the surface of earth. On the other hand, all the options are incorrect as they do not prevent from the UV radiation.

Therefore, Option (B) is correct.