0x55, because XRL performs bitwise XOR where each bit is inverted (AAH = 1010 1010, FFH = 1111 1111, XOR = 0101 0101 = 55H)

0xAA, unchanged because XOR with all 1s preserves the original value

0xFF, by setting all bits to 1 through the XOR operation

0x00, by clearing all bits through exclusive OR