Answer:
Directory traversal
Step-by-step explanation:
SQL injection is a hacking technique used to attack SQL (Structured Query Language) database, in which malicious SQL statements are inserted into an entry field in other to gain access to unauthorized information or make alteration to important data, thus option 1 is not the answer
Command injection is an attack in which an hacker execute arbitrary commands on a server, thus option 2 is wrong.
XML injection is an attack in which the hacker seek to inject xml tags and data into a database so as to exploit the logic of the application, option 3 is also wrong.
Directory traversal also known Path Traversal is a web attack in which the attacker access files in directories other than the root directory. thus option 4 is correct.