Mary is planning to buy a mobile phone that costs $500. She can choose any of five different payment plans with varying simple interest rates and periods: plan 1: 6% for 10 months plan 2: 8% for 12 months plan 3: 10% for 14 months plan 4: 12% for 18 months plan 5: 14% for 12 months Which plan offers the lowest monthly payments? A. plan 1 B. plan 2 C. plan 3 D. plan 4 E. plan 5