Monarch Butterflies

[ronnie1985]

Which of the following best completes the passage below?
Monarch butterflies, whose average life span is nine months, migrate from the midwestern United States to selected forests outside Mexico City. It takes at least three generations of monarchs to make the journey, so the great-great-grandchildren who finally arrive in the Mexican forests have never been there before. Yet they return to the same trees their forebears left. Scientists theorize that monarchs, like homing pigeons, map their routes according to the earth's electromagnetic fields. As a first step in testing this theory, lepidopterists plan to install a low-voltage transmitter inside one grove of "butterfly trees" in the Mexican forests. If the butterflies are either especially attracted to the grove with the transmitter or especially repelled by it, lepidopterists will have evidence that______
(A) monarch butterflies have brains, however minuscule
(B) monarch butterflies are sensitive to electricity
(C) low-voltage electricity can affect butterflies, whether positively or adversely
(D) monarchs map their routes according to the earth's electromagnetic fields
(E) monarchs communicate in intergenerationally via electromagnetic fields

OA [spoiler](B)[/spoiler]

What's wrong with (D)???

[eagleeye]

Answer should be B. Let me explain:

The argument premise is that, if monarch butterflies go near or stay farther from the tree, what can be DEFINITELY concluded:

(A) monarch butterflies have brains, however minuscule
This is not even under contention. Magnets are bulbs are affected by electricity, they don't have brains. NO

(B) monarch butterflies are sensitive to electricity
YES. Clearly, if the low-voltage (electric) device, attracts the monarchs or keeps them away, they must be sensitive to it.

(C) low-voltage electricity can affect butterflies, whether positively or adversely
Out of scope, this talks about all butterflies. NO

(D) monarchs map their routes according to the earth's electromagnetic fields
This device is located at the end of the journey in a tree in Mexico. This does not tell us whether the monarch butterflies use earth's EM field while migrating from US to Mexico. NO

(E) monarchs communicate in intergenerationally via electromagnetic fields
Out of scope, we don't know whether monarchs themselves produce magnetic fields. NO

Let me know if this helps