31. Assume a rm With constant marginal costs Who sells Good 1 has hired an econometrician to estimate the market demand. The econometrician has determined that q = 3 p1 3\" pin}?!3 , where p1 is the price of Good 1, p; is the price of a competing good, and A is the rm's advertising budget. What is the profitmaximizing markup for Good 1? Hint: Recall that the LernerIndex equals lflsl and the optimal markup equals 1/(1-L) A. L = p 2:46. = 1/ 3 , implying the optimal markup is 150% over costs B L = P 331C = 1/ 2 , implying the optimal markup is 200% over costs C. L = P 134C = 2 I 3, implying the optimal markup is 500% over costs D. L = P _ MC = 4 I 5, implying the optimal markup is 500% over costs