The scatterplot shows the relationship between the length of time , in hours, a certain bird spent in flight and the number of days after January 11, .
Based on the scatterplot, during which of the following time intervals did the bird's average flight time decrease at the greatest rate?
From January 12 to January 13
From January 14 to January 16
From January 16 to January 18
From January 19 to January 21
