Answer:
B
Step-by-step explanation:
It's B
3^5 = 243
so the 5th root of 243 is 3
(x^7)^(1/5) = x^(7/5)
(y^10)^(1/5) = 7 ^(10/5) = 7^2
z^(21)^(1/5) = z^(21/5)
