Isn’t the answer all of the above? They all seem like they are all connected. D leads to C, C leads to B, B leads to A, and A finally leads to “No, this is Patrick”
In the poem, Paradise is depicted as a series of concentric spheres surrounding the Earth, consisting of the Moon, Mercury, Venus, the Sun, Mars, Jupiter, Saturn, the Fixed Stars, the Primum Mobile and finally, the Empyrean.