A shop owner uses a linear regression model to predict ice cream sales based on temperature. The residual plot shows residuals randomly scattered around zero with no apparent pattern. What does this indicate about the linear model? Select one: a. The linear model is appropriate; the residuals suggest a good fit. b. The residuals plot indicates the presence of outliers affecting the model. c. The linear model is inappropriate; the residuals suggest a poor fit. d. The residuals plot suggests a nonlinear relationship is more suitable