Answer:
f(x) = 4^x
Step-by-step explanation:
In f(x) = (1/4)^x, 1/4 is equal to 0.25, which is less than 1, so its decreasing
In f(x) = 4^x, 4 is greater than 1, so its increasing
In f(x) = (0.4)^x, 0.4 is less than 1, so its decreasing
This is why f(x) = 4^x is the correct answer
I hope this helps!