You have found a mutual fund that you like and want to analyze the fee structure. The fund has class A and class B shares. Class A shares have a 4% front load, no back load, and no 12b-1 fees. Class B shares have no front load, a 5% back load that falls by 1% for each full year invested and has a 0.50% annual 12b-1 fee. You anticipate that the fund will return 12% per year after other fees not mentioned above (e.g. mgt fees) and plan to invest $10,000. After four full years (just beginning year 5) which of these two above  share classes would you prefer?