In circuit in following fig. the value of is
0
1
Fluctuates between 0 and 1
Indeterminate as the circuit can’t be realised
Lower gate inverts input to zero.
gate from
gate inverts this output to 1 upper
gate converts this input 1 and input 0 to 1 .
Thus become inputs of NAND gate giving final output as zero.
Hence option 1 is correct.