Which equation most accurately represents the rate of heat leaving the hot, H, stream for the steady-state heat exchanger shown? Pay attention to the direction of the arrows and the

labels. \mathbf{a} \quad \dot{\mathbf{Q}}=\dot{\mathbf{m}}_{\mathbf{a}}\left(\mathbf{h}_{\mathbf{a}}-\mathbf{h}_{b}\right) \text { b } \quad \dot{Q}=\dot{m}_{a}\left(h_{b}-h_{z}\right) c \quad \dot{Q}=\dot{m}_{a}\left(h_{b}-h_{a}\right)+\dot{m}_{x}\left(h_{x}-h_{y}\right) \mathbf{d} \quad \dot{\mathrm{Q}}=\dot{\mathrm{m}}_{\mathrm{a}}\left(\mathrm{h}_{\mathrm{a}}-\mathrm{h}_{\mathrm{b}}\right)+\dot{\mathrm{m}}_{\mathrm{x}}\left(\mathrm{h}_{\mathrm{y}}-\mathrm{h}_{\mathrm{x}}\right) \text { e } \quad \dot{Q}=\dot{m}_{a}\left(h_{b}-h_{a}\right)+\dot{m}_{x}\left(h_{y}-h_{x}\right) \mathbf{f} \quad \dot{\mathrm{Q}}=\dot{\mathrm{m}}_{\mathrm{a}}\left(\mathrm{h}_{\mathrm{a}}-\mathrm{h}_{\mathrm{b}}\right)+\dot{\mathrm{m}}_{\mathrm{x}}\left(\mathrm{h}_{\mathrm{x}}-\mathrm{h}_{\mathrm{y}}\right)