一道prepCR Public health official题目

yueyinnnnnn

Public health official: Some researchers suspect that magnetic fields from high-voltage power lines can cause health problems for people who live especially near the fines. However, this is extremely unlikely: beyond a distance of a few feet, the strength of the magnetic fields from high-voltage power lines is less than the average strength of magnetic fields in homes that are not located near such lines.
Which of the following would it be most useful to establish in order to evaluate the public health argument?
A． Whether magnetic fields in homes that are not located near high-voltage power lines can cause health problems for the residents of those homes
B．What proportion of people who live near high-voltage power fines believe that those fines may cause health problems
C．Whether high-voltage power lines are routed near residential in urban areas
D．What specific diseases or conditions are suspected by some researchers to result from exposure to magnetic fields from high-voltage power lines  
E．What is the average strength of magnetic fields in workplaces that are not located near high-voltage power lines
答案选A，求问D为什么不对

yueyinnnnnn

附上解释：
What additional evidence would most help determine whether magnetic fields from high-voltage power lines cause health problems for people who live near the lines? The public health official argues that 发电磁场可能不会在线路的几英尺外带来健康问题，因为这些磁场比远离这些fines的家庭更弱 This argument assumes that magnetic fields in homes far from the fines不会带来健康问题 and 住在靠近fines的家庭不会花很多时间在几英尺的地方 Therefore, look for an answer option that indicates whether one or both of these assumptions is correct.
A. Correct. This information would straightforwardly indicate whether the first assumption discussed above is true.
D. Without further information (e.g., whether the incidence of such diseases or conditions is greater among people who live especially near higher-voltage power fines), knowing which specific health problems the researchers think the fines cause would suffice to evaluate the public health argument.     
还是不太理解D的解释

Bradz

题目讨论的是磁场会不会造成健康问题，不是会造成什么健康问题

yueyinnnnnn

嗯嗯 明白啦，多谢大牛指点！