please explain 18 to 21 with steps thanks

... . A. 35 B. 50 C. 45 D. 40 Questions 14 - 21 are based on the following information: Consider a hypothetical computer in which the processor has four registers: a 24-bit Program Counter (PC), a 64-bit Accumulator (AC), and an Instruction Register (IR). The system bus has 48 wires for address and 64 wires for data. The memory is divided into words each of which is 64-bit long. Each word can hold either an instruction or a piece of data. For each instruction X, the ten most significant bits (denoted by X63-54) represent an opcode. The rest of the instruction (denoted by X53-0) can be either a direct address or an immediate value of an operand, as shown below 63 54 53 0 Opcode Address/Immediate Value Operands that represent signed numbers are interpreted according to the two's complement representation. The table below explains some of the instructions supported by the processor and shows the CPI for each instruction: Opcode (Binary) Operation 0001100011 Load AC from the memory location whose address is given in the instruction 0010100101 Store AC to the memory location whose address is given in the instruction Add the content of the memory location whose address is given in the instruction to the 0011100111 content of AC 0101101011 Add the immediate value that is given in the instruction to the content of AC The AC has the value 00000000000000FF initially 14) What is the length of the IR? A. 24 B. 32 C. 48 D. 64 15) How many different instructions that this processer could support? A. 256 B. 512 C. 1024 D. 2048 16) What is the range of memory locations that programs' instructions can occupy? A. 000000 - FFFFFF B. 0000 - FFFF C. 00 FF D. None of them 17) What is the range of memory locations that programs' data can occupy? A. 000000 - FFFFFF B. 0000 - FFFF C. 00 - FF D. None of them 18) What is the maximum size of installed memory that can be supported in the system, even if it cannot be addressed by the processor? A. 256 GB B. 256 TB C. 4 GB D. 64 GB 19) What is the maximum negative integer number that can be used as an immediate value in an instruction? A. -253 - 1 B. -253 C.-254-1 D. -1 20) After executing the instruction 5AFF0000000000ED, what would be the value of the AC A. 00000000000000FF B. FF000000000000ED C. FFFF0000000001EC D. 00000000000000ED 21) Which instruction would store the contents of AC to memory location 3FFOOABCDEF123 A. 5AFFFOOABCDEF123 B. 5A3FFOOABCDEF123 C. 293FFOOABCDEF123 D. 297FFOO