The correct option is A. (4m−7n)(16m2+28mn+49n2)We have, 64m3−343n3=(4m)3−(7n)3
Using x3−y3=(x−y)(x2+xy+y2)
Here x=4m and y=7n
⇒(4m)3−(7n)3
=(4m−7n){(4m)2+(4m)(7n)+(7n)2}
=(4m−7n)(16m2+28mn+49n2)