2 is correct answer. fig 2, b and c have {f,g} as upperbound. but for the graph to be a lattice it should have a least upper bound. Since b and c have two upper bounds they cannot have a least upper bound<which is always unique for a pair for vertices>. In other words we cannot say which one is least one out of the pair {f,g}. therefore it is not a join semilattice(every pair of element should have a least upper bound). henceforth it is also not a lattice
