Concept:The African Development Bank (AFDB) is a regional financial institution that supports economic and social progress in African member countries.
Explanation:The AFDB mainly provides loans and technical assistance to member nations.
These loans are used to finance viable projects that promote development.
Projects may include infrastructure, agriculture, education, and health.
Option A, promoting free trade, is not the main function of the AFDB.
Option B, financing balance-of-payment problems, is not its primary role.
Option D, helping members overcome internal problems, is too vague and not specific to the bank's purpose.
Thus, the main function is clearly to lend money to members for feasible and productive projects.
This matches the description of the bank's lending activities and development objectives.
Answer:C. Provide loans to members to finance viable projects.