Step 1: Understanding the Concept.
The Indian Constitution divides legislative subjects into the Union List, the State List, and the Concurrent List, where the Concurrent List holds subjects both Parliament and state legislatures can legislate on.
Step 2: Check the options.
Criminal law and criminal procedure (which includes the Code of Criminal Procedure) are placed in the Concurrent List, which is why both Parliament and state assemblies can amend procedural criminal law within their powers. This rules out the State List alone, the Union List alone, and any combination that excludes the Concurrent List.
Step 3: Final Answer.
Criminal procedure falls under the Concurrent List, so option B is correct.