Consider two different implementations (P1 and P2) of an instruction set architecture. The instructions can be divided into four classes (Classes A, B, C and D). P1 has a clock rate of 2.5 GHz and CPls of 1, 2, 3, and 3, for the four instruction classes, respectively; P2 has a clock rate of 3 GHz and CPI of 2 for all the classes. Given a program with an instruction count of 1.0E6 instructions that are divided into four classes as follows: 10% class A, 20% class B, 50% class C, and 20% class D. Which of the following statements is/are true? O a. The overall CPI for P1 is 2.5. O b. The overall CPI for P2 is 2. O c P2 is faster. d. P1 is faster