You create a custom Web Part.

You need to create a class to log Web Part errors to the Unified Logging Service (ULS) logs.

What should you use?

A.
the ILogger interface

B.
the ILoggingProvider interface

C.
the SPDiagnosticsServiceBase class

D.
the SPPersistedObject class

Explanation:
MNEMONIC RULE: “Unified Logging Service = SPDiagnosticsServiceBase”

Logging to ULS in SharePoint 2010
http://blog.mastykarz.nl/logging-uls-sharepoint-2010/