Calculate the work done in blowing a soap bubble to a radius of 1 cm. The surface tension of the soap bubble is 2.5 x 10⁻² N/m.

a) 2.5 x 10⁻⁴ J
b) 5 x 10⁻⁴ J
c) 7.5 x 10⁻⁴ J
d) 1 x 10⁻³ J