A thin liquid film formed between a U-shaped wire and a light slider supports a weight of $$1.5 \times 10^{-2}$$ N (see figure). The length of the slider is $$30$$ cm and its weight negligible. The surface tension of the liquid film is

A

$$0.0125\ Nm^{-1}$$

B

$$0.1\ Nm^{-1}$$

C

$$0.05\ Nm^{-1}$$

D

$$0.025\ Nm^{-1}$$