GRE Reading Comprehension
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Source: XDF
The two claws of the mature American lobster are decidedly different from each other. The crusher claw is short and stout; the cutter claw is long and slender. This bilateral asymmetry begins to appear in the juvenile sixth stage of development. One possible explanation is that differential use of the claws determines their asymmetry; the claw that is used more becomes the crusher.
To test this hypothesis, researchers raised lobsters in the juvenile fourth and fifth stages of development in a laboratory environment in which the lobsters could manipulate oyster chips. Under these conditions, the lobsters developed asymmetric claws, half with crusher claws on the left, and half with crusher claws on the right. In contrast, when juvenile lobsters were reared in a smooth tank without the oyster chips, the majority developed two cutter claws. This unusual configuration of symmetrical cutter claws did not change when the lobsters were subsequently placed in a manipulatable environment or when they lost and regenerated one or both claws.
It can be inferred that of the two laboratory environments mentioned in the passage, the one with oyster chips was designed to
- A prove that the presence of oyster chips was not necessary for the development of a crusher claw.
- B prove that the relative length of time that the lobsters were exposed to the oyster-chip environment had little impact on the development of a crusher claw
- C eliminate the environment as a possible influence in the development of a crusher claw
- D control on which side the crusher claw develops
- E simulate the conditions that lobsters encounter in their natural environment