Do p electric currents, by means of the electromagnetic fields that accompany them, cause cancer in people who live and work nearby Telephone line workers, who work near such currents every day, can provide a test case. They show elevated levels of brain cancer; therefore, the hypothesis of electromagnetic causation is supported.
Which of the following, if true, most seriously weakens the argument
A．Burying power lines and other measures to protect the public from such electromagnetic fields would be prohibitively expensive.
B．Telephone line workers are exposed to levels of chemical solvents high enough to cause brain cancer.
C．High exposure to p electromagnetic fields is correlated with a slightly higher-than-normal incidence of childhood leukemia, which is a form of cancer.
D．Public health officials who found that a group of different illnesses in people living near a power substation could not reliably be attributed to its electromagnetic field were accused of covering up the facts.
E．(E) Telephone line workers, like most people have electrical appliances at home, and most electrical appliances, when turned on, are surrounded by an electromagnetic field of some measurable level.