Answer:
Option A is correct.
is a function represents a transformation of f(x) by a vertical stretch with factor of 1.25.
Explanation:
Given the function:

For a base function f(x) and a constant k > 0, the function is given by:
g(x) = kf(x), can be sketched by vertically stretching f(x) by a factor of k
if k>1.
Since, factor(k) = 1.25 > 1.
then;
.......[1]
Substitute
in [1];

Therefore, the function represents a transformation of f(x) by a vertical stretch with factor 1.25 is,
