Much of this frozen glaciers and ice caps, so we don't consider is usable. a. salt water b. fresh water c. rainwater d. ice

Much of this frozen glaciers and ice caps, so we don't consider it usable freshwater.

This statement tells about the freshwater usage out of the whole water available on earth some are stored in the form of glaciers, ice caps, etc. Which cannot be used as freshwater.

practical process described pest part of scientific investigation.

because practical knowledge is powerful then therotical knowledge.