China's Mineral Deposits
China's vast territory and complicated geological formations create favorable conditions for mineralization. Rich mineral deposits are found on the plains and in the mountains.
Reserves of over 50 metals and nearly 80 non-metals have been discovered, in addition to rich fuel-bearing deposits. These include rich deposits of nonferrous metal, rare-earth metal, coal and certain non-metals. The proved reserves of a number of minerals are among the richest in the world, including rare earth, coal, iron, copper, tin, lead, zinc and aluminum. The prospects for petroleum and natural gas are also bright. The abundance of minerals provides a solid material basis for the country's modernization.
Nevertheless, there are also some inadequacies. Most of the minerals are unevenly distributed and the prospects of some reserves are not clear. Insufficient reserves have been proved for some minerals: others, such as iron and copper, do not usually occur in rich veins.
The reserves of quite a number of minerals are among the largest in the world, but the per capital amount is smaller than that in many other countries.
Although China has conducted a great many preliminary surveys, the work has to be in tensified in the eastern part of the country, and it has hardly begun in many places in the west. Prospecting and exploitation are still rather backward. China has only just opened the door to its underground treasure house, where the mysteries have by no means been uncovered. With the progress in geological research and exploration, more and better minerals will be found.
Which minerals have been proved to be insufficient？

A. Lead and aluminium.
B. Rare-earth metal and coal.
C. Zinc and tin.
D. Not indicated directly.