Assume, you are given two lists: a= [1,2,3,4,5] b=[6,7,8,9] The task is to create a list which has all the elements of a and b in one dimension. Output: a= [1,2,3,4,5,6,7,8,9] Which of the following option would you choose? a.append(b) a.extend(b) Any of the above None of these