Hi @Arjun sir ,
Please correct me if I am wrong.
In option (ii) , LUB of (a,b) is b and LUB of (b,d) is b.
So , the pair (a,b) and (b,d) does not have unique LUB.
Similarly the pair (a,c) and (d,c) does not have unique LUB.
So, it is not lattice.
Am I wrong ?