Select the correct answer.
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