Which of the following is a true statement regarding the relative merits between access rights enforcement based solely on a kernel as opposed to enforcement provided largely by a compiler?
A.Enforcement by the compiler provides a greater degree of security.
B.Enforcement by the kernel is less flexible than enforcement by the programming language for user-defined policy.
C.Kernel-based enforcement has the advantage that static access enforcement can be verified off-line at compile time.
D.The fixed overhead of kernel calls cannot often be avoided in a compiler-based enforcement.
正确答案是B