Background

Recall that for a function $f(x,y)$ that has two independent variables, the parial derwatives can be meresented either using the notasion $fx\frac{\text{d}\text{e}\text{l}\text{f}}{\text{d}\text{e}\text{l}\text{z}}$; both represent the partial denivative of the function $f$ with respect to the independent valuate $r.$ Similaty, for partial derivatives with respect to the independent wariabies $y,$ the leos notations are $f_y(r,y)$ and $\frac{\text{d}\text{e}\text{l}\text{f}}{\text{d}\text{e}\text{l}\text{y}}.$

Question

In the context of the wave equation for a ware propagating through a mediu, what does the function as $(3\mathrm{.}7,t)$ represen?

A The rate of change of the wave's amplifule over lime at any lime$,$ f $.$ for the soeclly poirt $x=3\mathrm{.}7$ in the medium.

C The rate of charge of the wave's anplitude over lime all lime $f=3\mathrm{.}7$ for ary point, an the medium.

medium.