A) Over the past 10 years, no pandas have been imported to the United States.
This statement, if true, supports the conclusion that tougher international restrictions on importing pandas are not to blame for the recent shortage of pandas in U.S. zoos. However, it doesn't directly address the reasons for the shortage, such as decreased reproduction rates and increased upkeep costs.
B) Since there are fewer pandas in the world today than 10 years ago, zookeepers have found it difficult to secure pandas for their zoos, especially since the cost to secure and support the panda is twice that of any other animal.
This statement supports the argument by providing additional context that there are fewer pandas available globally, making it harder for zookeepers to secure pandas for their zoos. Additionally, the increased cost of supporting pandas compared to other animals adds to the challenges. Therefore, this strengthens the conclusion that factors other than international restrictions are responsible for the shortage of pandas in U.S. zoos.
C) The recent drought in China and southeastern Asia has severely decreased the bamboo shoots available for pandas to eat throughout the world.
While this statement provides relevant information about the availability of bamboo, which is the primary food source for pandas, it doesn't directly strengthen the conclusion that tougher international restrictions are not to blame for the shortage of pandas in U.S. zoos.
D) A recent study has concluded that the animal people look forward to seeing the most at zoos is the koala bear.
This statement is irrelevant to the argument about the shortage of pandas in U.S. zoos and does not provide any support for the conclusion.
E) An increase in the number of zoos throughout the United States has increased the demand for pandas by medium-sized and small zoos.
While this statement suggests an increase in demand for pandas, it doesn't address the reasons for the shortage or whether tougher international restrictions are to blame.
Based on the analysis, option B provides the most effective support for the conclusion by explaining why zookeepers may have difficulty securing pandas for their zoos, aligning with the argument that factors other than international restrictions contribute to the shortage. Therefore, option B is the correct choice.