In this task, you are given inputs 'i', 'j', and A, where 'i' and 'j' are integers and A is a list. A list is shown by two brackets and comma-separated numbers and characters inside, like ['1', '12', 'l']. You need to concatenate all elements of A from the ith element to the jth element, and then reverse the resulting string. 'i' and 'j' will be non-negative, and will always have a value less than the length of A. 'i' will always be less than 'j'. Perform the operations in order, i.e., do not reverse first and then concatenate.
5, 20, ['6121', '6311', 'n', 'J', '2397', 'L', '7173', 'Q', '5227', 'R', 'g', 'm', '5883', '8175', '7085', 'v', '9851', '9989', 'x', '5311', '8435', 'q', '987', 'M', 'c', '6829', '4941', 'B']