The correct option is B Near the hydrogen chloride bottle
When a bottle of dry HCl and NH3 are connected, HCl and NH3 react to form NH4Cl, which is white in colour. The first white ring will be formed near the bottle which contains the gas that diffuses at a lesser rate than the other.
Using Graham's law of diffusion
Rate of diffusion is inversely proportional to the molecular weight of the gas i.e r∝M
So, rNH3rHCl=√MHClMNH3
HCl has a higher molecular weight than ammonia and so will diffuse at a lesser rate than ammonia. Hence the first ring will be formed near the HCl bottle.