The correct answer is C. MIPS.
IPS stands for instructions per second. It is a measure of how many instructions a CPU can execute per second. CIPS stands for clock cycles per instruction. It is a measure of how many clock cycles it takes a CPU to execute one instruction. MIPS is a more accurate measure of CPU performance than IPS because it takes into account the complexity of the instructions being executed.
Nanoseconds are a unit of time equal to one billionth of a second. They are not used to measure CPU performance.
E is not the correct answer because it is not a valid unit of measurement for CPU performance.