Australian researchers have discovered electroreceptors
(sensory organs designed to respond to electrical fields)
clustered at the tip of the spiny anteater’s snout. The
researchers made this discovery by exposing small areas of
(5) the snout to extremely weak electrical fields and recording
the transmission of resulting nervous activity to the brain.
While it is true that tactile receptors, another kind of
sensory organ on the anteater’s snout, can also respond to
electrical stimuli, such receptors do so only in response to
( 10) electrical field strengths about 1,000 times greater than
those known to excite electroreceptors.

Having discovered the electroreceptors, researchers are
now investigating how anteaters utilize such a sophisticated
sensory system. In one behavioral experiment, researchers
(15) successfully trained an anteater to distinguish between
two troughs of water, one with a weak electrical field
and the other with none. Such evidence is consistent with
researchers’ hypothesis that anteaters use electroreceptors
to detect electrical signals given off by prey; however,
( 20) researchers as yet have been unable to detect electrical
signals emanating from termite mounds, where the favorite
food of anteaters live. Still, researchers have observed
anteaters breaking into a nest of ants at an oblique angle
and quickly locating nesting chambers. This ability quickly
(25)to locate unseen prey suggests, according to the
researchers, that the anteaters were using their electroreceptors
to locate the nesting chambers.

Which of the following, if true, would most strengthen the hypothesis mentioned in lines 17-19?

(A) Researchers are able to train anteaters to break into an underground chamber that is emitting a strong electrical signal.
(B) Researchers are able to detect a weak electrical signal emanating from the nesting chamber of an ant colony.
(C) Anteaters are observed taking increasingly longer amounts of time to locate the nesting chambers of ants.
(D) Anteaters are observed using various angles to break into nests of ants.
(E) Anteaters are observed using the same angle used with nests of ants to break into the nests of other types of prey.

Hi Turtle,

This RC question is a disguised CR strengthening question.

The conclusion is that anteaters use electrical signal to detect their prey. In the premises it is given that the anteater can distinguish water trough of weak electrical signal. It is also given that the anteater is able to quickly find the nesting chamber of ants.

(B) Researchers are able to detect a weak electrical signal emanating from the nesting chamber of an ant colony.

If researchers are able to detect a weak signal then it means that the anteater is using the weak electrical signal to detect its prey. We can say this because it is given in the passage that the anteater can detect a weak electrical signal in a water trough. As compared to other choices (B) gives us a strengthener to the researchers' hypothesis

Hope this helps,

Vercules
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hypothesis that anteaters use electroreceptors
to detect electrical signals given off by prey; however,
( 20) researchers as yet have been unable to detect electrical
signals emanating from termite mound

from this text we can reach B , D is irrelevant to discussion and even may weaken because if they use various angles then how can we say that they are using electroreceptors ? E is better because single angle means some thing being detected but still we need additional assumption that angle depends on the electric field. In strengthen and weaken we do get such nicely crafted options which seem relevant but need additional assumption, these are always wrong. the hypothesis must be strengthened with the answer choice only and no additional information added.

B tells they have detected a weak signal from ant's nest , that they were unable to detect from termite mound. thats mentioned in passage . and that strengthens
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