Explanation:

- Petya:

- A form of ransomware that encrypts the master file table (MFT) of a hard drive and demands a ransom to unlock it.

- First identified in 2016, it spread rapidly and affected many organizations globally.

- Locky:

- A ransomware that encrypts files and demands payment for their release.

- Distributed primarily through email attachments and was first identified in early 2016.

- WannaCry:

- A global ransomware attack in May 2017, exploiting a vulnerability in Microsoft Windows.

- Known for its rapid spread and significant impact on various industries.

- All of the above:

- Correct Answer

- All mentioned options are examples of ransomware, which is malicious software designed to block access to a computer system until a sum of money is paid.

Each of the listed options has notably contributed to the surge in ransomware cases worldwide.