Jane is studying the rate at which the sale of a particular brand of chocolate has increased over the years. The graph below shows the number of bars sold y, in thousands, after x years since the year 2000:

graph of y equals 15 multiplied by 1.1 to the power of x

What does the y-intercept of the graph represent?

Price of a bar of chocolate
Number of bars sold in 2000
Number of bars sold before 2000
Rate of increase in the sale of chocolates