Concept:Simplify nested radicals step-by-step from the innermost to the outermost using basic arithmetic and cube roots.Explanation:Start with the innermost part: 49​=7.Then inside the cube root: 722+7=729. The cube root 3729​=9 because 93=729.Now 16+9​=25​=5.Then 59+5=64. The cube root 364​=4 because 43=64.Answer:D. 4