data communication and networking. Roll.num: Sp19-bse-005 Question #04 [CLO: C3] [Marks: 12] a) Why is a medium access protocol necessary? What is slotted ALOHA and Un-slotted ALOHA? (4) b) Perform CRC. The divisor is 4+2+1+1 and the dividend is1s complement of 8-bit binary of your registration number. Perform operations on both senders and receivers side.(5) c) The data is 10110110,11001010,00101011,10101111. Perform two dimensional parity check code. (3)