How is phosphine prepared using the following reagents?
$$\begin{array} { l l } { \text { (a) } } & { \mathrm { HCl } } \\ { \text { (b) } } & { \mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } } \\ { \text { (c) } } & { \text { Caustic soda } } \end{array}$$