TOEFL Reading: ETS-TOEFL阅读机经 - SQRUSD6X053U8836L$

Which of the following questions is NOT answered by paragraph 5? A. What causes colonies to have problems with their food supplies? B. What are the disadvantages of colonial nesting? C. What percentage of cliff swallow nests are infected by parasites? D. How can one test the different hypotheses explaining the evolution of bird colonies?