The correct answer is A. Hacking.
Hacking is the unauthorized access into a computer system. It is often done to steal data, damage files, or disrupt operations. Hackers can use a variety of methods to gain access to a system, including exploiting vulnerabilities in software, guessing passwords, or social engineering.
Encryption is the process of converting data into a form that cannot be read without a key. It is used to protect data from unauthorized access. Decryption is the process of converting encrypted data back into its original form.
None of these is the correct answer.