Users report that the database on the main server cannot be accessed. a database administrator verifies the issue and notices that the database file is now encrypted. the organization receives a threatening email demanding payment for the decryption of the database file. what type of attack has the organization experienced?

This kind of attack is best known as a Ransomware attack. Ransomware attacks, if allowed to gain access to an IT environment, could shut down an organization or deny access to mission critical data and applications. Ransomware viruses are introduced into the servers and end up encrypting data and demands ransom for its release.
An example of a known Ransomware virus is Samas. Samas exploits known vulnerabilities and then encrypts hundreds of different file types. Samas and other forms of Ransomware demands payments in bitcoins so that data can be decrypted. 

Sorry i don’t know the answer to this