A. Forked Process shares the address space and other resources with parent.
False, forked process creates a whole new copy of the process including the stack and data and code sections.
B. Forked Process can't use multiprocessor for parallel execution.
False, they are two different processes now and hence they can use multiprocessor for parallel execution when available.
C. Security is better in Process in comparison to threads.
True, since threads share stack, maybe they would overwrite each others' data so it can be a little less secure. (which by the way is very unlikely)
Edit: as threads share the address space of a process, so any modification/changes made by one thread is reflected in other threads as well. This makes threads less secure than processes. [source]
D. Thread switching doesn't require Kernel Support unlike threads.
I think you meant to say 'Thread switching doesn't require Kernel Support unlike processes.'
This is true in case of user level threads, they do not need to switch to kernel mode and do context switching like that. The user level threads (of the same process) doesn't require kernel support. But the kernel level threads do require the support from Kernel to switch. Hence the statement D is not always true.
False.