What is the complete factorization of 4x^2-9y^4?

A. 36 (x^2-y^4)

B. 4x^2 (1-9y^4)

C. (2x+3y^2) (2x-3y^2)

D. (2x-3y^2) (2x-3y^2)

Use the difference of squares factor rule to get

4x^2-9y^4

(2x) ^2 - (3y^2) ^2

(2x-3y^2) (2x+3y^2)

The final answer is choice C

Note: the order of the factors does not matter