The correct answer is B.
$N^2 = {(7601)}_8$
$N^2 = 7 * 8^3 + 6 * 8^2 + 0 * 8^1 + 1 * 8^0 $
$N^2 = 3969$
$ N = 63 $
Now consider the option
A. ${(241)}_5 = 2 * 5^2 + 4 * 5^1 + 1 * 5^0 = 50 + 20 + 1 = 71 $ (Not an answer)
B. ${(143)}_6 = 1 * 6^2 + 4 * 6^1 + 3 * 6^0 = 36 + 24 + 3 = 63 $ (Its the answer)
Rest you can check.