When a function is stretched vertically, every function value is multiplied by the stretch factor. Here that factor is 5. Multiplying f(x) by 5 gives ...
A stretch of the graph of a function is like a little piece of that function that is located in the graph similarly to the other graph, and it says that it is a factor of 5, that means that the graph is being multiplied by 5, so from the options you can search for options where the f(x) is being multiplied by 5 is the last one, d. g(x)=5f(x) .
