Which of the following is an application of surface tension?

Question

$\begin{array}{1 1} \text{(a) Use of soaps and detergents as cleansing agents} \\ \text{ (b) Molecular structure can be elucidated by surface tension measurements through parachor values} \\ \text{ (c) Surfactants are incorporated in preparations like toothpaste} \\ \text{ (d) All of the mentioned} \end{array}$