A model just means which function best fits the data. If you plug your values into a list on your graphing calculator and turn on your diagnostics, you can determine which function closely fits the data.
Turn on your diagnostics. This allows you to determine what's called the "correlation coefficient". The closer this value is to 1 or -1, the better the fit. For linear, the correlation coefficient R2=.96. For quadratic, the R2=.99. For exponential, the R2=.91. This means quadratic is the best fit, very good actually since .99 is very close to 1. Hope this helps.
