Which polynomial function f(x) has a leading coefficient of 1, roots -4,2, and 9 with multiplicity 1, and root -5 with multiplicity 3

"polynomial function f(x) has a leading coefficient of 1"
So because of that, we can eliminate A and B.
Now we have "root –5 with multiplicity 3"
That's just product of three factors (x+5)
So D is wrong.
We are left with the only possible correct option C.
C is f(x)= (x + 5)(x + 5)(x + 5)(x + 4)(x – 2)(x – 9) 

Shoutout to: @Geerky42

Answer is: C: f(x)= (x+5)(x+5)(x+5)(x+4)(x-2)(x-9)

Have an amazing day!