I need help with this question please

OO DOC OOO OOO OOO Which expressions represent the number of circles in Step n? DJ() - 34 3(7 -1) for 7 2 1 Of () - 34 2(n -1) for n > 1 D (1) -3, f (n) - 2+1(n -1) torn > 2 D /(1) - 3, f (7) - 3+f(7 -1) torn = 2 D f (m) = 3n for n 2 1 D / (m) = 3+ 3n for n > 1