Jen, Eric, and Kurt Are All Buyers of Chain Saws

Jen, Eric, and Kurt are all buyers of chain saws. Jen's demand function is Q_j = 520 - 13P, Eric's demand function is Q_e = 40 - P, and Kurt's demand function is Q_k = 200 - 5P. Together, these three constitute the entire demand for chainsaws. At what price will the price elasticity of market demand be 21?

A) $19
B) $20
C) $25
D) $15
E) none of the above.