$19.$ A wave can be described by the function $()().$ What is the speed of this wave? A$)1\mathrm{.}0$ m$/$s B$)2\mathrm{.}0$ m$/$s C$)3\mathrm{.}0$ m$/$s D$)4\mathrm{.}0$ m$/$s E$)5\mathrm{.}0$ m$/$s