(4 point) MIPS instructions are classified into R-type, I-type and J-type. I-type has the following fields: OpcodeRs 16 R-type has the following fields: Opcode Rs Rd Shamt FunctCode Please explain why we assign the bits to each field as above? (i.e. why use 6 bits for opcode, 5 bits for registers, and 16 bits for Immediate.) What is the functCode in R-type used for? Why Opcode in R-type also uses 6 bits? a. b. c