Digital-ME Worbook #2

Question

To this I am getting answer as (d). Please confirm.

Comments

I think the answer must be (a). X and Y will be fixed at 0 and 1 respectively.

Answer 1

Whatever be the initial input, once B gets input 0 it will turn the output Y to 1.

Now the input to the A's NAND gate are 1 and 1 which makes the output at X as 0.

Now when input at B changed to 1 from 0, the B's NAND gate will have inputs 1 and 0 which will keep the output at Y at 1.

Hence now whatever input is given to B, the output will not change unless the input to A changes.

Hence A is the answer.