Respuesta :
Answer: The correct option is (C) y = 4x.
Step-by-step explanation: We are given to identify the function in which y varies directly with x.
We know that
if y varies directly as x, then we write as follows :
[tex]y\propto x\\\\\Rightarrow y=k\times x~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~[\textup{where k is the constant of proportionality}]\\\\\Rightarrow y=kx~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(i)[/tex]
Out of the given options, equation (i) matches with the third option y = 4x, for k = 4.
Therefore, the correct option is (C) y = 4x.