Joe, a User, Cannot Read Encrypted Email Messages on a Corporate

Multiple Choice

Joe, a user, cannot read encrypted email messages on a corporate smartphone, but he has been able to read them in the past. A technician restarts Joe's smartphone, but the issue remains. The technician deletes the corporate email account and has Joe re-add it, verifying all settings are correct. Despite these steps, the issue persists. Which of the following is MOST likely causing the issue?

A) The certificate is expired.
B) The TPM is bad.
C) The phone is not encrypted.
D) The incorrect mail server is selected in settings.