18. One of the following statements is correct about shift registers: a. They can be used in serial transfer b. They are the same as asynchronous counters c. They are the same as ripple counters d. None of the above 19. A ROM of size 32G X 32 has: a. 32 input lines b. 5 output lines c. 35 address lines d. None of the above 20. A RAM that is able to store 8 gigabytes (assuming a word size of 8 bits) has a decoder of size: a. 33 x 233 b. 32 x 232 c. 8 x 28 d. 5 x 32