Of all the option given, ore is the most valuable and concerned material to mine for metals.
Answer: Option A
Explanation:
Ore is the impure composition or form of metal. Thus, mining for ore, will help extract metal. Mining is the process of valuable material such as metals or precious stones or natural resource.
The Earth has the depository for several valuable material at many place inside the surface of the Earth. Digging through several techniques lets to find the impure forms of those valuable material.
Ore is such form for the metal. Other option given are water which do not be mined unless for potable waters, soil are weathered and mined for precious stones and woo is an insignificant option.