Given:
The composition of functions is G(F(y)).
To find:
The independent variable of G(F(y)).
Solution:
Independent variable is the variable whose value independent from other variable. It means the value of independent variables is not depend on the other variable.
We know that G(F(y)) can be written as
Here, the value of function G depends on F(y) and the value of F(y) depend on variable y. But value of y does not depend on any variable. So, y is the independent variable of G(F(y)).
Therefore, the correct option is C.
