Kieran owns and operates his own bike shop. in the past week, he received two offers: one to work for a competitor for $50,000 per year and one to sell his bike shop for $100,000. assume the annual interest rate is 6 percent, and kieran is indifferent between owning his bike shop or working for the competitor. kieran currently receives enough annual revenue to cover all explicit costs and has $60,000 left over. there are no additional implicit costs (excluding the items listed above). under these circumstances, kieran's economic profit is equal to which of the following? a $96,000b $90,000c $4,000d $10,000e $60,000