In which sphere would lightning be found? with explanation
a. atmosphere
b. magnetosphere
c. biosphere
d. hydrosphere

The answer is:  [A]:  atmosphere .

Explanation:  Lightning does occurs in the "atmosphere".  (Think: clouds/weather).

There is no such thing as the "magnetosphere", in terms of the "4 (FOUR) spheres---geosphere, biosphere, atmosphere, hydrosphere.

Lightning would not be found in the "biosphere"; lightning is not an "organic" process; nor does it directly occur in or within the ecosystem or living environment.

Lightning, in and of itself, it independent of the "hydrosphere"/ hydrologic cycle/hydrologic processes that occur on Earth.