A rectangular film of liquid is extended from $$(4cm\times2cm)$$ to $$(5cm\times4cm)$$. If the work done is $$3\times10^{-4}$$ J, the value of the surface tension of the liquid is

A

$$0.125 Nm^{-1}$$

B

$$0.2 Nm^{-1}$$

C

$$8.0 Nm^{-1}$$

D

$$0.250 Nm^{-1}$$