Correct Option: B

Some economists have classified factors into two categories, land and labour (or nature and man) on the ground that they are the only original or primary factors. It is said that capital has no independent origin and is merely the outcome of combined efforts of land and labour. However, other economists include all man-made instruments for production in the category of Capital. It includes machines, tool, factories, buildings, canals, roads, raw materials, etc, which play vital role in production.