Which polynomial is a perfect square trinomial?

9x2 - 12x + 4

36b2 - 24b + 16

16x2 - 24x - 9

4a2 - 10a - 25

9x² - 12x + 4

9x² - 6x - 6x + 4

3x (3x) - 3x (2) - 2 (3x) - 2 (-2)

3x (3x - 2) - 2 (3x - 2)

(3x - 2) (3x - 2)

(3x - 2) ²

36b² - 24b + 16

4 (9b) - 4 (6b) + 4 (4)

4 (9b² - 6b + 4)

16x² - 24x - 9

4a² - 10a - 25

The answer is A.