Identify the polynomial that is the difference of two squares.

25m2 - 16n

36m2 - 8n8

49m2 - 81n4

9m2 - 5n6

We know that

The difference of two squares is a squared number subtracted from another squared number. Every difference of squares may be factored according to the identity

(A ²-B²) = (A+B) * (A-B)

so

the answer is

49m2 - 81n4

49m2 - 81n4 = (7m+9n²) * (7m-9n²)