A heat engine absorbs heat q1 from a source at temperature $T_1$ and heat $ q_2$ from a source a temperature $T_2$. Work done is found to be $J(q_1+q_2)$. This is in accordance with

Question

$\begin {array} {1 1} (A)\;\text{1st law of thermodynamics } & \quad (B)\;\text{2nd law of thermodynamics} \\ (C)\;\text{Joules equivalent law} & \quad (D)\;\text{None of these} \end {array}$