The scatter plot below shows the relationship between drop height and speed of a roller coaster.

the linear equation that best models this data is y=0.216x+32.575

(question) What does the y-intercept of this graph represent?
(Response1) it represents the height of a roller coaster before it drops
(response2) it represents the average speed of a roller coaster ride
(response3) it represents the speed of a roller coaster at a drop height of 0 feet
(response4) it represents the average height of a roller coaster