Which is the polynomial function of lowest degree with rational real coefficients, a leading coefficient of 3 and √5 and 2?
a. f(x)=3x³ - 6x² - 15x + 30
b. f(x)=x³ - 2x² - 5x + 10
c. f(x)=3x² - 21x + 30
d. f(x)=x² - 7x + 10