The projected sales volume of a video game cartridge is given by the function s (p) = 3000/(2 p + a) where s is the number of cartridges sold, in thousands; p is the price per cartridge, in dollars; and a is a constant. If according to the projections, 100,000 cartridges are sold at $10 per cartridge, how many cartridges will be sold at $20 per cartridge?

(A) 20,000

(B) 50,000

(C) 60,000

(D) 150,000

(E) 200,000