Suppose that Sara is contemplating whether to spend the money to buy a promotional ski card for this upcoming season. Their utility function for skiing and all other goods is given by U=x*s+2*x, such that their marginal utility for skiing is given by U_s=x and their marginal utility for other consumption is U_x=s+2. Assume that Sara has $600 of disposable income to allocate across these goods, and that the price of a daily lift ticket is $100. Use a price of $1 for the indexed other goods (i.e. the budget constraint has intercept at x=600 and s=6.) If a promotional discount offers Sara the chance to ski for half price, but the card costs $100, how many days will she ski? Select one: O a. They won't ski at all. cross out O b. 1 day cross out O c. 2 days cross out O d. 3 days cross out O e. 4 days cross out Of. 5 days cross out O g. 6 days cross out