just 3 questions

Which of the following statements can add a new node pointed by new_node in front of the node containing 30 correctly? 30 50 head new_node 10 Which of the following statements can insert the node pointed by the pointer cur after the node pointed by the pointer ptr into the list correctly? struct Node Type { T data; Node Type* prev; NodeType* next; 1; NodeType* ptr, cur; 40 10 ptr cur- 20 Which of the following statements can remove the node with the value 30 pointed by cur from the list and release the memory space occupied by this node correctly? struct Node Type 1. T data; Node Type* prev; NodeType* next; NodeType* cur; 10 30 50 cur