Factor the polynomial 4x4 – 20x2 – 3x2 + 15 by grouping. What is the resulting expression?

(4x2 + 3)(x2 – 5)
(4x2 – 3)(x2 – 5)
(4x2 – 5)(x2 + 3)
(4x2 + 5)(x2 – 3)

The correct answer is (4x² - 5)(x² - 3)