The shaft work done by the fluid in a reversible flow process in which there are no changes in the kinetic, potential and surface energies, is given by

(a) \(W_{\text {shaft }}=\int_{1}^{2} P d V\)

(b) \(W_{\text {shaft }}=\int_{2}^{1} P d V\)

(c) \(W_{\text {shaft }}=\int_{2}^{1} V d P\)

(d) \(W_{\text {shaft }}=\int_{1}^{2} V d P\)