I don’t understand this Algebra question and need help to study.

Simplify the expression below. Assume all variables are nonnegative real numbers.

fourth root of left parenthesis 3 x minus 1 right parenthesis to the power of 4 end root

A. open vertical bar 3 x minus 1 close vertical bar

B. 12x-4

C. 3x-1

D. No real number