Describe the difference between simple and compound interest.. Choose the correct answer below. OA. Simple interest involves interest calculated only on the principal. Compound interest is interest computed only on the accumulated interest. OB. Simple interest is interest computed on the original principal as well as on any accumulated interest. Compound interest involves interest calculated only on the principal. OC. Simple interest involves interest calculated only on the principal. Compound interest is interest computed on the original principal as well as on any accumulated interest. OD. There is no difference between simple and compound interest.