To operate economically, the incremental costs must be equal for both generators. Therefore, we equate the derivatives of the cost functions with respect to \(P_1\) and \(P_2\):
\[
\frac{dC_1}{dP_1} = \frac{dC_2}{dP_2}
\]
This gives:
\[
0.1 = 0.2
\]
Solving this equation gives:
\[
P_1 = P_2 = 100 \, \text{MW}
\]
Thus, the economic operation occurs when both generators are producing 100 MW, which corresponds to option (1).