What is the domain of the relation? {(−4.5, 0), (−3, 9), (0.9, 0), (4, −7.8), (4, 0), (17, 3)}

{0.9, 4, 17}

{−7.8, 0, 3, 9}

{−4.5, −3, 0.9, 4, 17}

{−4.5, −3}