John, a junior workflow developer, has approached you for advice on a workflow process that he is defining. He is unclear about the implications of selecting the Runnable checkbox while defining the Process Activity. What advice would you offer?（）

A. Runnable allows the workflow engine to compile the process.
B. Runnable allows the process to be included as a stand-alone subprocess.
C. Runnable allows the workflow engine to check its status during process execution.
D. Runnable allows the workflow engine to define this as a top-level process and initiate it