Some species of dolphins find their prey by echolocation; they emit clicking sounds and listen for echoes returning from distant
objects in the water. Marine biologists have speculated that those same clicking sounds might have a second function: particularly loud clicks might be used by the dolphins to stun their prey at close range through sensory overload. Which of the following, if discovered to be true, would cast the most serious doubt on the correctness of the speculation described above? (A) Dolphins that use echolocation to locate distant prey also emit frequent clicks at intermediate distances as they close in on their prey.
(B) The usefulness of echolocation as a means of locating prey depends on the clicking sounds being of a type that the prey is incapable of perceiving, regardless of volume.
(C) If dolphins stun their prey, the effect is bound to be so temporary that stunning from far away even if possible, would be ineffective.
(D) Echolocation appears to give dolphins information about the richness of a source of food as well as about its direction.
(E) The more distant a dolphin's prey, the louder the echolocation clicks must be if they are to reveal the prey's presence to the hunting dolphin.
(B) The usefulness of echolocation as a means of locating prey depends on the clicking sounds being of a type that the prey is incapable of perceiving, regardless of volume.
If the prey can't really hear the echolocation, there is no potential for "sensory overload," which would discredit the theory that they stun their prey. It sounds pretty cool, but I feel like the speculation is probably unfounded.
Bacteria that do not take up any plasmids would grow only on nutrient broth without antibiotics.
This is because antibiotics from the broth will kill bacteria. If bacteria took the plasmid that carries the resistance genes for ampicillin and/or tetracycline it would grow on media containing that antibiotics.
