You are creating a Web Part that will be deployed as a sandboxed solution.

You need to ensure that the Web Part can write debugging information to the SharePoint trace logs.

Which class should the logging component inherit?

A.
SPDelegate

B.
SPLog

C.
SPPersistedObject

D.
SPProxyOperation

Explanation:
MNEMONIC RULE: “sandboxed solution needs SPProxyOperation”

You can implement your full-trust functionality in classes that derive from the SPProxyOperation abstract class and deploy the assembly to the global assembly cache. These classes expose a full-trust proxy that you can call from within the sandbox environment.

Full-trust proxies can provide a useful way to expose logging and configuration functionality to sandboxed applications.

Hybrid Approaches
http://msdn.microsoft.com/en-us/library/ff798433.aspx