Given:
The intial amount with Kimberly is, I = $500.
The savings amount each month is, s = $50.
The objective is to find the correct function which can be use to determine the amount after x months.
Step-by-step explanation:
Since, the intial amount is already fixed. But the saving amount is added for each month upto x months.
Then, the monthly saving can be expressed as,

To find function:
Now, the total savings as a function can be calculated as,

Thus, the required function to calculate the amount after x months is f(x) = 50x+500.
Hence, the correct answer is option (C).