Detailed Instructions: In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.
Q: Question: What year did buddhism come to Thailand? Passage:There is no official state religion in the Thai constitution, which guarantees religious freedom for all Thai citizens, though the king is required by law to be a Theravada Buddhist. The main religion practised in Thailand is Buddhism, but there is a strong undercurrent of Hinduism with a class of brahmins having sacerdotal functions. The large Thai Chinese population also practises Chinese folk religions, including Taoism. The Chinese religious movement Yiguandao (Thai: Anuttharatham) spread to Thailand in the 1970s and it has grown so much in recent decades to come into conflict with Buddhism; in 2009, it was reported that each year 200,000 Thais convert to the religion. Many other people, especially among the Isan ethnic group, practise Tai folk religions. A significant Muslim population, mostly constituted by Thai Malays, is present especially in the southern regions.
 Links: a. Thai language b. Thailand c. Isan d. Hinduism
A:
b