Explain why the cost of obtaining some minerals is very high

Some minerals are found in complex compounds, and it is difficult (and expensive) to separate the mineral from that compound. In other cases, the mineral may be found in remote areas, with greater costs to reach it. In others, the mineral may be buried under great depths of overburden, increasing the cost to reach the mineral layer. The cost of energy and transporting mining equipment to remote areas is greater, and there may be a shortage of labor. And sometimes, the mineral is at a very low ratio of mineral to waste- it will be necessary to mine and remove a LOT of material to recover a very small amount of mineral.

The minerals are expensive you have to dig some of them up and they are worth alot

a is the answer i believe.