4. Which of the following can be inferred about anteaters from the behavioral experiment mentioned in the second paragraph?
      (A) They are unable to distinguish between stimuli detected by their electroreceptors and stimuli detected by their tactile receptors.

　　(B) They are unable to distinguish between the electrical signals emanating from termite mounds and those emanating from ant nests.

　　(C) They can be trained to recognize consistently the presence of a particular stimulus.

　　(D) They react more readily to strong than to weak stimuli.

　　(E) They are more efficient at detecting stimuli in a controlled environment than in a natural environment.

　　5. The passage suggests that the researchers mentioned in the second paragraph who observed anteaters break into a nest of ants would most likely agree with which of the following statements?

　　(A) The event they observed provides conclusive evidence that anteaters use their electroreceptors to locate unseen prey.

　　(B) The event they observed was atypical and may not reflect the usual hunting practices of anteaters.

　　(C) It is likely that the anteaters located the ants' nesting chambers without the assistance of electroreceptors.

　　(D) Anteaters possess a very simple sensory system for use in locating prey.

　　(E) The speed with which the anteaters located their prey is greater than what might be expected on the basis of chance alone.

　　6. 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.