Acertain function f consists of two steps, step1 and step2. all f does is execute step1 then execute step2. as a function of an input parameter n, step1 takes running time t1(n) and step2 takes running time t2(n). describe the running time of f as a function of t1(n) and t2(n). for which of the following values of t1(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) t1(n) is n2, t2(n) is n3: o(n2)
(b) t1(n) is n3, t2(n) is 2n: o(n32n)
(c) t1(n) is n, t2(n) is n log2n: o(n2 log n)
(d) t1(n) is n3, t2(n) is 2n: o(2n)