A system has 4 kg of fluid $$(C_{v}=0.8)$$ that expands in a friction less piston from initial state of 1 MPa, $$200^\circ C$$ to 1 MPa, $$100^\circ C$$. What is the network (in kJ), if there is no heat transfer?

A

-160

B

-80

C

80

D

160