Which is the fully factored form of 49x^30-21x^15+7x^5?

7x^5(7x^25-3x^10+1)

7x^5(7x^6-3x^3+x)

7x^5(7x^25-3x^10)

7x^5(7x^6-3x^3)

The fully factored form of 49x^30-21x^15+7x^5 is 7x^5(7x^25-3x^10+x).