David earned 10 percent on the $200,000 he invested in a special account at his credit union. Interest was paid semi-annually. His effective rate of interest was: Select one: O a. 10.55% O b. 10.25% C. 10.56% O d. 15.75%

David earned 10 percent on the $200,000 he invested in a special account at his credit union. Interest was paid semi-annually. His effective rate of interest was: Select one: a. 10.55% b. 10.25% c. 10.56% d. 15.75%