请选出以下Python代码中能够正确实现归并排序合并两个有序子数组功能的merge函数是？

def merge(left, right):
    merged = []
    i = j = 
    while i < len(left) and j < len(right):
        if left[i] <= right[j]:
            merged.append(left[i])
            i += 1
        else:
            merged.append(right[j])
            j += 1
    return merged

def merge(left, right):
    merged = []
    i = j = 
    while i < len(left) and j < len(right):
        if left[i] <= right[j]:
            merged.append(left[i])
            i += 1
        else:
            merged.append(right[j])
            j += 1
    merged.extend(left[i:])
    merged.extend(right[j:])
    return merged

def merge(left, right):
    merged = []
    i = j = 
    while i < len(left) or j < len(right):
        if left[i] <= right[j]:
            merged.append(left[i])
            i += 1
        else:
            merged.append(right[j])
            j += 1
    return merged

def merge(left, right):
    merged = []
    i = j = 
    while i < len(left):
        merged.append(left[i])
        i += 1
    while j < len(right):
        merged.append(right[j])
        j += 1
    return merged