Which is the polynomial function of lowest degree with rational real coefficients, a leading coefficient of 3 and roots StartRoot 5 EndRoot and 2? f (x) = 3 x cubed minus 6 x squared minus 15 x 30 f (x) = x cubed minus 2 x squared minus 5 x 10 f (x) = 3 x squared minus 21 x 30 f (x) = x squared minus 7 x 10.