At the end of a project, you upload project documents to a Microsoft SharePoint Online library that contains many files. The following is a sample of the project document file names: ✑ aei_AA989.docx ✑ bci_WS098.docx ✑ cei_DF112.docx ✑ ebc_QQ454.docx ✑ ecc_BB565.docx All documents that use this naming format must be labeled as Project Documents: You need to create an auto-apply retention label policy. What should you use to identify the files? 

Answer options:

A. A sensitive info type
B. A retention label
C. A trainable classifier

C

Reference: https://docs.microsoft.com/en-us/microsoft-365/compliance/classifier-get-started-with?view=o365-worldwide