question:  Which of these is NOT said to be a cause for headaches?
context: No one knew whether his Theory of Spatium was correct or not because no one had yet been able to frame an argument with it. The government took up a lot of his time using him as the symbol of the Ideal Scientist to help recruit Science and Engineering Cadets. Despite his impressive body, some years before he had suffered a mild stroke ... or at least a vascular spasm of a cerebral artery. It was known that he suffered from the vilest variety of migraine. "Doctor, we understand you have severe headaches," Mitchell said. "That's right, Steven. Migraine." "Doctor," Mitchell said, "what would you say the most common complaint of man is?" "I would have said the common cold," Macklin replied, "but I suppose from what you have said you mean headaches." "Everybody has them at some time in his life. "Aspirins would still be used to reduce fever and relieve muscular pains," Mitchell said. "There are a number of different causes for headaches—nervous strain, fatigue, physical diseases from kidney complaints to tumors, over-indulgence—but there is one effect of all of this, the one real cause of headaches," Mitchell announced. "The pressure effect caused by pituitrin in the brain," Mitchell said eagerly. "That is, the constriction of blood vessels in the telencephalon section of the frontal lobes. It's caused by an over-production of the pituitary gland. A colony of virus in the brain cells will relax the cerebral vessels—and only the cerebral vessels—so that the cerebrospinal fluid doesn't create pressure in the cavities of the brain." "On rats, on chimps...." Conscientious objectors from the Army." Unless we can produce quick, conclusive and dramatic proof of our studies we can get no more financial backing. When I start making slips like that it means another attack of migraine. "When your heart stops, your blood pressure goes to its lowest point," Mitchell said.
output:  UV rays
options:  nervous strain  fatigue  over-indulgence  UV rays