12.30 Consider the following program that deadlocks. Initially: a Thread 1: P(a); P(b); V(b); P(c); V(c); V(a); = 1, b = 1, c = 1. Thread 2: P(c); P (b); V(b); V (c); P(a); V(a); Thread 3: P(c); V(c); P(b); P(a); V(a); V(b); A. For each thread, list the pairs of mutexes that it holds simultaneously. B. If a < b