HELP I NEED HELP ASAP

Based on what i know about mean, this doesn't add up.

Will give find an equivalent function to f(x)=5(2)^3x. the 5(2)^3x means 5(2) to the 3x power answer choices: a: f(x)=125^x(8)^x b: f(x)=10^2x c: f(x)=40^x d: f(x)=5(8)^x

Which expression is equivalent to 2x^2+7x+4?