Human capital refers to:

A. physical capital owned by households rather than businesses.

B. the accumulated financial wealth of households.

C. the skills and knowledge that enable a worker to be productive.

D. machinery used by labor in production.

C. the skills and knowledge that enable a worker to be productive.

Explanation:

'Human Capital' is the stock of knowledge & skills embodied in people, enabling them to perform labour of economic value. It is considered as 'capital' because skills & knowledge development to become more productive yields better income & standard of living.

Human Capital formation i. e knowledge, skills & productivity enhancement has two crucial components : Education and Health.

Options A, B, D are inapt because : Human Capital is not 'physical capital', 'financial wealth', 'machinery'; but is rather immaterial knowledge & skill set in people.