Concept:Simplify nested square roots by evaluating from the innermost root outward.Explanation:Start with the innermost root: 9​=3.Then 19−9​=19−3=16.So 16​=4.Next, 21+19−9​​=21+4=25.So 25​=5.Then 41−21+19−9​​​=41−5=36.Finally, 36​=6.Answer:The simplified value is 6, so the correct option is B.