单项选择题 Yuan Longping is known as China’s “father of hybrid rice”. His research for hybrid rice is （）。

单项选择题 In an American literature class, the students are assigned the task of carrying out a research to find out the current studies on William Faulkner’s “A Rose for Emily”, and writing a literature review on it. So what kind of research will it be?（）

单项选择题 Suppose you have met some translation errors in the English version of public signs in tourist attractions in Xi’an, you want to carry out a thorough research on it so as to reveal the current status, analyze the causes of the existing problems in translation and provide possible solutions to improve the situation. You plan to visit more tourist attractions to collect sources for your analysis and discussion. The sources you will collect in the tourist attractions are（）。