Iron Kangaroo is a large mining corporation based in Western Australia. Over the past several years, the company’s mines have become less productive and mines are frequently closed due to broken equipment. What is the BEST way for Iron Kangaroo to improve the productivity of the mines?A. The company should hire additional workers.

B.
The company should improve its workers’ human capital.

C.
The company should acquire more natural resources.

D.
The company should invest in new capital goods.