Many new cars provide detailed information about engine performance on the dashboard. One such feature allows drivers to observe current fuel efficiency, recorded in miles per gallon, as they drive. A consumer takes a long trip driving at different speeds, while a passenger records both driving speed in miles per hour and fuel efficiency for a number of selected points along the trip. A least-squares equation that relates speed to fuel efficiency is given by Efficiency = 0.104 (speed)-25.444.

Based on the residual plot shown, is a linear model appropriate for comparing driving speed and fuel efficiency?

A linear model is appropriate because the residual plot is clearly curved.
A linear model is not appropriate because the residual plot shows a clear pattern.
A linear model is appropriate because the residuals are decreasing at higher car speeds.
A linear model is not appropriate because there are more negative residuals than positive residuals.