Final answer:
The correct function to represent a geometric sequence is an exponential function typically expressed as f(x) = ar^x, not one of the provided options.
Step-by-step explanation:
The student is asking which function can be used to model a graphed geometric sequence. A geometric sequence has a constant ratio between consecutive terms. This means that each term is found by multiplying the previous term by a fixed, non-zero number called the common ratio. Therefore, the function that models a geometric sequence must involve exponentiation or multiplication by a constant to achieve the scaling effect inherent to geometric progressions.
Looking at the given options, the correct representation of a function for a geometric sequence is not listed. Typically, a geometric sequence can be represented by an exponential function like f(x) = ar^x, where a is the first term and r is the common ratio.