[tex]y=a^x[/tex]
The function is increasing if a > 0.
The function is decreasing if 0 < a < 1.
Therefore your answer is
[tex]A.\ f(x)=6^x[/tex]
[tex]6^x\to a=6 > 1\\(0.6)^x\to a=0.6 < 1\\\left(\dfrac{1}{60}\right)^x\to a=\dfrac{1}{60} < 1\\\\\left(\dfrac{1}{6}\right)^x\to a=\dfrac{1}{6} < 1[/tex]
