The table below contains a partial view of data about a random sample of 58 car makes and models, including number of cylinders, engine displacement (in cubic inches), passenger volume (in cubic feet), and CO2 emissions (in grams/km). Make Model Cylinders Engine Displacement Passenger Volume CO2 Emissions Hyundai Equus 8 5 111 502 MINI Cooper S Convertible 4 1.6 72 312 Porsche 911 Turbo S 6 3.8 70 457 Infiniti Q70 AWD 8 5.6 104 486 Cadillac CTS Sedan 4 2 97 372 BMW 328i xDrive 4 2 96 343 Mercedes-Benz CLA250 4matic 4 2 88 321 BMW 550i xDrive Gran Turismo 8 4.4 112 473 Kia Cadenza 6 3.3 106 404 BMW M6 Coupe 8 4.4 88 554 Volkswagen Jetta 4 1.8 94 301 Porsche 911 Carrera S Cabriolet 6 3.8 68 405 Dodge Challenger 6 3.6 94 425 BMW 328d 4 2 96 279 We want to create a regression model to analyze the relationship between CO2 and the specific attributes of the vehicle: the number of cylinders, the engine displacement, and the passenger volume. Based on this data table, how many independent variables are included in the model? 5 4 3 2