Five years ago, as a personal investment, Bob and Sue purchased a second mortgage on a single family residence in Minneapolis. The principal amount of the mortgage was $25,000 when they purchased it, but since it was a speculative investment, the purchase price was only $20,000 (or 80 percent of face value). The interest rate on the mortgage was 9 percent. For the first three years, Bob and Sue reported interest received plus 20 percent of each principal payment received as income, and 80 percent as return of capital. Last year, Bob heard about a rule that said the cost of a speculative investment can be recovered first, before reporting any income. Therefore, last year, Bob and Sue quit reporting 20 percent of each principal payment as income, and reported only interest income. They say they will report the remaining discount income after they recover their full $20,000 cost in the mortgage. a. Is this a change in accounting method? b. If this is a change from an erroneous accounting method to a proper method, can Bob and Sue file amended returns for the open years? c. If this is not a change in method, can Bob and Sue file