PLEASE HELP: I need a step-by-step explanation for this question

Answer:
C.
Step-by-step explanation:
Solve the equation by making a [tex]u[/tex] substitution to reduce the equation to a solveable form.
Exact Form: r = [tex]0[/tex] , [tex]\frac{9}{49}[/tex]
Decimal Form: 0, 0.18367346....