The correct answer is (B) To extract substances by the percolation of water or other liquids through materials, such as soil or ore; to make liquid percolate through some material in order to remove soluble materials; to subject material to the action of percolating liquid. Also, to wash soluble matter away.

Leach comes from Old English leccan (to water, irrigate).

Examples of use:

• The chemist used acid to leach the substance from the ore.
• The river has been polluted by chemicals leached from chemical fertilizers.