Review the table of values showing the number of days each year from 1990 to 1997 that air quality in San Diego did not meet federal air quality standards.

Which phrase best describes the regression model for the data?

power model; y = 41.21x–0.86
exponential model; y = 54.97(0.71)x
logarithmic model; y = 39.14 – 17.93 ln x
quadratic model; y = 0.60x2 – 10.38x + 46.73