1Mediumgeneral⏱ 45sWhat is the time complexity of the merge step in merge sort, and what is the overall complexity?📎▼AMerge step is O(1), overall O(n)BMerge step is O(n) per level, overall O(n log n)CMerge step is O(n^2), overall O(n^2)DMerge step is O(log n), overall O(n)