单选题 It can be inferred from physical phenomenon that

A、 the force of the electromagnetic field is too weak to be harmful
B、 the force of the electromagnetic field is weaker than the electric field that the cells generate
C、 electromagnetic field may affect health
D、 only more powerful radiation can knock electron out of human body

【正确答案】 A

【答案解析】细节理解题。答案在第四段第二、三句，当电流通过电缆，产生磁场，对周围物体产生(影响)力。许多年来，科学家把任何有关“这些力可能有害的想法”置于一边(不予考虑)，主要是因为它们(所产生的力)非常弱。