Firm 1 produces product a only, and firm 2 produces product b only. firm 3 produces the same amount of a as firm 1 and the same amount of b as firm 2. all three firms use state-of-the-art production techniques, but firm 3's total costs are less than the sum of the other two firms' total costs. we can conclude that there are

a. diseconomies of scope in producing products a and b.

b. economies of scope in producing products a and b.

c. increasing returns to scale in producing products a and b.

d. decreasing returns to scale in producing products a and b.