The equation \( f(x) = 400(1.15)^t \) represents an exponential growth scenario, where the initial value is 400 and it increases by a factor of 1.15 for each time unit \( t \).
The best representation of this equation is:
A population of birds that starts at 400 and grows 15% annually.
This scenario aligns with the equation because it starts with an initial population of 400 and grows at a rate of 15% (1.15 factor) over time.