Why length of PC and sp are of 16 bit?

The program counter (PC) and stack pointer (SP) in a 16-bit architecture are typically 16 bits long to match the architecture's addressable memory space. With 16 bits, the PC can address up to 65,536 memory locations (2^16), allowing access to the complete addressable range of a typical 16-bit system. This alignment ensures efficient memory management and facilitates direct addressing of program instructions and stack operations.