Which of the Following Statements About Critical Sections Is False

Which of the following statements about critical sections is false?

A) Only one thread at a time can execute the instructions in its critical section for a particular resource.
B) If one thread is already in its critical section, another thread must wait for the executing thread to exit its critical section before continuing.
C) Once a thread has exited its critical section, a waiting thread may enter its critical section.
D) All threads must wait whenever any critical section is occupied.