Answer: [tex]C. f(x) = 3(2^x)[/tex].
Step-by-step explanation:
If the graph of function y=f(x) is vertically stretched by a scale factor of 'k', then the new function will be :
[tex]Y=kf(x)[/tex]
The given function : [tex]f(x)=2^x[/tex]
If the given function vertically stretched by a scale factor of '3', then the new function will be :
[tex]Y=3f(x)=3(2^x)[/tex]
Hence, the correct option is [tex]C. f(x) = 3(2^x)[/tex].