Question 2 (1 points): Suppose two threads A and B coordinate using a spinlock implemented based on atomic exchange like we dicussed in lecture. Assume, unlike xv6's spinlocks, these threads do not disable interrupts when acquiring the spinlock. Both threads are running on a single-core system that uses a round-robin scheduler with a 20 millisecond time quantum. Thread A acquires the spinlock, then needs to do about 50 milliseconds of computation, then will release the spinlock and terminate. About 1 millisecond after thread A acquires the spinlock, thread B tries and waits to acquire the spinlock. Assuming thread A and B are the only runnable threads on the system (and never need to wait for I/O), how long will it be between when thread A acquires the spinlock and when it releases it? A. O about 50 milliseconds B. O about 70 milliseconds C. O about 90 milliseconds D. O about 100 milliseconds E. O about 110 milliseconds F. O about 130 milliseconds G. O about 150 milliseonds H. O A will never release the spinlock