If the earth is 70% water, why do we have droughts?

Unequal distribution of water resources on earth.

Explanation:

As the earth has 70% of the water that is stored in the ocean, sea, river and the glaciers as freshwater and even water present underground all which part of the hydrological cycle is insufficient and inefficient to meet the daily requirement of the people on earth. Due to this the rest 29% of the land that experiences drought conditions either due to the lack of rains or due to the increasing heat waves from the sun and maybe resulting from overgrazing and overpopulation.

Ithink the answer to that would be b):