Answer: B)Kernel threads
Explanation: Kernel thread is defined as the kernel mode task.It usually has a slow processing for the creation and management. This thread comes under the scheduler so, the task done by the thread is scheduled by the system and then processes it.
Other given option are incorrect because Processes and Light weight process are the task performed by the system for processing and User level threads are the threads that are handled by the programmer.Thus the correct option is option(B).