What are the most common reasons that the BitLocker Drive Encryption recovery password is required?

What will be an ideal response?

The most common reasons that the recovery password is required are:
* Modified boot files-If one of the boot files on the system volume is modified, BitLocker Drive Encryption stops the system from starting because the operating system has been tampered with.
* Lost encryption keys-If there is a problem with the TPM and the encryption keys stored in it are lost or corrupted, then the encrypted volume cannot be decrypted normally. The recovery password is also required if the encryption keys are stored on a USB drive that is lost or erased.
* Lost or forgotten startup PIN-If the requirement for a startup PIN is selected and the user forgets the startup PIN, then the recovery password is required to access the encrypted data.