Which one of these runtime notations are wrong?

Q1(12 points): Asymptotic Notations (a) (4 points) Which one of the following is wrong?? l. (n) +O(n)= (n) 2.(n) + (n) = (n) 3. (n) + 0(n)=0(n) 4, f(n) = 0(g(n)) implies g(n) = (f(n)) (b)(4 points) Which one of the following sorting algorithms will have the best best-case running time? 1. Selection sort 2. Insertion sort 3. Heap sort 4. Quick sort (c)(4 points) Explain why the statement, "The running time of an algorithm is (1)," is meaningless