Identical wire loops are dipped into liquid a and liquid b, so that a film of liquid forms across the loops (like the bubble solution on a child's bubble blowing wand). the width of each loop is increased slowly and the forces fa and fb needed to make the loops 5% wider are measured.
(a) fa will be greater than fb
(b) fa will be less than fb
(c) fa will be equal to fb
(d) it is impossible to predict whether fa or fb will be greater without more information.