The fixed proportion of working capital should be generally financed from the ____ capital sources.

correct answer is A. fixed capital sources.

This is based on the financial principle of matching the maturity of assets and liabilities:

Permanent (or Fixed) Working Capital refers to the minimum level of current assets that a firm must maintain at all times to conduct business operations (e.g., minimum inventory, minimum cash). Since this investment is required throughout the year and is permanent in nature, it should be financed from long-term (fixed) sources of capital, such as equity, debentures, or long-term loans.

The working capital means CA-CL i.e. invested by long-term capital. The long-term fund is either the owner's fund or borrowed but it should be fixed. So fixed portion of working capital should be financed by fixed capital.