A US Company and a Japanese Company Sells an Identical Product

A U.S. company and a Japanese company sells an identical product in the Japanese market. The inverse demand equation for this product is P_J = 5 !0.2(Q_JUS + Q_{J J}) . Suppose that the best-response functions of the U.S. and Japanese companies are Q_JUS = 5 !0.5Q_{J J} and Q_{J J} = 7.5 !0.5Q_JUS, respectively. The Cournot-Nash equilibrium {Q_{J US}, Q_JJ} in the Japanese market is:

A) {6.67, 6.67}.
B) {3.33, 8.33}.
C) {8.33, 3.33}.
D) {1.67, 6.67}.
E) {6.67, 1.67}.