下面的代码片段用于反转单链表，请进行（ ）修改，使其能正确实现相应功能。
ListNode* reverseLinkedList(ListNode* head) { ListNode* prev = nullptr; ListNode* current = head; while (current != nullptr) { ListNode* next = current->next; current->next = next; prev = current; current = next; } return prev; }
current->next = next; 应该改为 current->next = prev;
ListNode* next = current->next; 应该改为 ListNode* next = prev->next;
current != nullptr 应该改为 current->next != nullptr
ListNode* prev = nullptr; 应该改为 ListNode* prev = head;