A Firm's First-Order Condition from the Cournot Game with General $P ( Q ) q _ { i } - C _ { i } \left( q _ { i } \right) = 0$

Multiple Choice

A firm's first-order condition from the Cournot game with general demands and costs is

A) $P ( Q ) q _ { i } - C _ { i } \left( q _ { i } \right) = 0$ .
B) $P ( Q ) - C _ { i } ^ { t } \left( q _ { i } \right) = 0$ .
C) $P ( Q ) + P ^ { t } ( Q ) \sum _ { j = 1 } ^ { n } q _ { j } - C _ { i } ^ { t } \left( q _ { i } \right) = 0$ .
D) $P ( Q ) + P ^ { t } ( Q ) q _ { i } - C _ { i } ^ { t} \left( q _ { i } \right) = 0$ .