Please provide detailed step-by-step solutions! Will give thumb-up for a good answer. Thank you!

4. A certain function f consists of two steps, Stepl and Step2. All f does is execute Stepl then execute Step2. As a function of an input parameter n, Stepl takes running time Ti(n) and Step2 takes running time T2(n) Describe the running time of fas a function of Ti(n) and T2(n). For which of the following values of Ti(n) and T2(n) is the big-oh running time of function f stated the closest possible approximation to the true running time of f? a) Ti(n) is n2, T2(n) is n3: O(n) b) Ti(n) is n2, T2(n) is n3: O(n3) c) Ti(n) is n, T2(n) is n log2n: O(n) d) T^(n) is r3, T2(n) is 2": O(r3)