Answer:
The model that best describes the relationship between g and t is an exponential function

Explanation:
In this problem we have a exponential function of the form

where
g(t) represent the gallons of water after evaporating
t is the number of hours
a is the initial value or y-intercept of the exponential function
b is the base
r is the rate
b=(1+r)
In this problem we have
---> initial gallons of water into the bucket
---> is negative because is a decay rate

substitute

therefore
The model that best describes the relationship between g and t is an exponential function