So you need to put both the equation in the y equals if you have a graphing calculator
Then you compare the two equation
f(x) is an decay and g(x) is growth
For choice one and three, the answer choice doesn't make sense leaving you with two and four as the only ones.
Since f(x) is a decay, it cant be choice four either leaving choice 2 as the final answer
This makes sense because g(x) is a growth
I hope this helps!