In the world's aquifers, around______of freshwater is stored as groundwater.

Concept: Groundwater is the water display underneath Earth's surface in shake and soil pore spaces and within the breaks of shake arrangements. 

Around 30 percent of all readily accessible freshwater within the world is groundwater. 

A unit of shake or an unconsolidated store is called an aquifer when it can abdicate a usable amount of water.

Hence, the correct answer is option A.