Please help me, thanks

What is thought to have caused the mass extinction at the end of the cretaceous period?

Which of the following is not a symptom of desertification? a) decrease in salt content of the soil b) lowering of the water table c) reduced surface water d) increased soil erosion e) loss of native vegetation

Which statement best describes a typical difference that could be found between the "analysis" and "conclusion" sections of a lab report? a) only the "conclusion" describes errors that occurred during the experiment, and only the "analysis" section suggests further research. b) only the "analysis" section includes specific data comparisons, and only the "conclusion" section suggests further research. c) only the "analysis" section discusses whether the original hypothesis was supported, and both sections include graphs of data. d) only the "conclusion section discusses whether the original hypothesis was supported, and both sections suggest further research.(the answer is b i just took the test)