Definition: In this task, you're given a question, along with a context passage. The passage will not have a direct answer to the question, but can include some information and a clue for the answer. Assuming you can only obtain information about one entity in the passage, your job is to determine whether information from the passage can be used to answer the question. Indicate your choice as `a` for Yes or `b` for No.
Input: Question: Was Nathan Sivin alive when Han Zhenhua claimed that Nanhai referred to the Scarborough Shoal? Passage:The People's Republic of China and the Republic of China (Taiwan) claim that Chinese people discovered the shoal centuries ago and that there is a long history of Chinese fishing activity in the area. The shoal lies within the nine-dotted line drawn by China on maps marking its claim to islands and relevant waters consistent with United Nations Convention on the Law of the Sea (UNCLOS) within the South China Sea. An article published in May 2012 in the PLA Daily" states that Chinese astronomer Guo Shoujing went to the island in 1279, under the Yuan dynasty, as part of an empire-wide survey called "Measurement of the Four Seas" (四海测验), however, no such 13th century map has been made public by China nor such evidence on the existence of the map is known. In 1979 historical geographer Han Zhenhua (韩振华) was among the first scholars to claim that the point called "Nanhai" (literally, "South Sea") in that astronomical survey referred to Scarborough Shoal. In 1980 during a conflict with Vietnam for sovereignty over the Paracel Islands (Xisha Islands), however, the Chinese government issued an official document claiming that "Nanhai" in the 1279 survey was located in the Paracels. Historical geographer Niu Zhongxun defended this view in several articles. In 1990, a historian called Zeng Zhaoxuan (曾昭璇) argued instead that the Nanhai measuring point was located in Central Vietnam. Historian of astronomy Chen Meidong (陈美东) and historian of Chinese science Nathan Sivin have since agreed with Zeng's position in their respective books about Guo Shoujing.


b