Option a. isn't always correct and RISC instruction set can have more instructions than CISC. For reference, one can read Wikipedia page on RISC which states that in many cases, RISC set will have more instructions than CISC. "Reduced" in RISC means less work and not less instructions.
A common misunderstanding of the phrase "reduced instruction set computer" is the mistaken idea that instructions are simply eliminated, resulting in a smaller set of instructions. In fact, over the years, RISC instruction sets have grown in size, and today many of them have a larger set of instructions than many CISC CPUs. Some RISC processors such as the PowerPC have instruction sets as large as the CISC.