A hunter who is a bit of a braggart claims that, from a distance of 1.8 km, he can selectively shoot eiither of two squirrels who are sitting 11 centimeters apart on the same branch of a tree. What's more, he claims that he can do this without the aid of a telescopic sight on his rifle. Determine the diameter of the pupils of his eyes that would be required for him to be able to resolve the squirrels as separate objects. In this calculation use a wavelength of 498 nm (in vacuum) for the light.