Like Jupiter and Saturn,Neptune Emits About 2

Multiple Choice

Like Jupiter and Saturn,Neptune emits about 2.5 times as much heat energy as it receives from the Sun,although calculations show it should have already lost all of its original heat.What is the most likely explanation?

A) Unlike Uranus,it is still contracting.
B) Radioactive decay has kicked into overdrive,with runaway reactions taking place.
C) The basis for these calculations is currently being questioned by a new generation of scientists.
D) There are gravitational anomalies taking place,which may hold some clue as to where the heat may be coming from.
E) Uranus' gravity is creating a "slingshot" effect,catapulting solar winds into Neptune's atmosphere in the form of as of yet undetected radiation.