You create a sandboxed solution that contains a Web Part.

You need to debug the Web Part by using Microsoft Visual Studio 2010.

To which process should you attach the debugger?

A.
owstimer.exe

B.
spucworkerprocess.exe

C.
spucworkerprocessproxy.exe

D.
w3wp.exe

Explanation:
MNEMONIC RULE: “Sandbox worker needs no proxy”

To provide additional protection, the solutions assembly is not loaded into the main IIS process (w3wp.exe). Instead, it is loaded into a separate process (SPUCWorkerProcess.exe).

Sandboxed Solution Considerations
http://msdn.microsoft.com/en-us/library/ee231562.aspx

If the project type lets you change the Sandboxed Solution property and its value is set to true, then the debugger attaches to a different process (SPUCWorkerProcess.exe).

Debugging SharePoint Solutions
http://msdn.microsoft.com/en-us/library/ee231550.aspx