You will be given a definition of a task first, then some input of the task.
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.

Question: Which of the organizations that are represented on YBF's advisory board has the highest membership numbers? Passage:As of September 2010, YBF's "advisory board" includes Matthew Elliott, founder of the UK TaxPayers' Alliance, and representatives of the Heritage Foundation (a US conservative thinktank), US Competitive Enterprise Institute and American Conservative Union (a US conservative lobbying organisation). It also includes the founder of the US Leadership Institute, the President of the US Jesse Helms Center, the President of the Young America's Foundation, the co-founder of the US Henry Jackson Society and a former Executive Director of the Collegiate Network. British representatives include Professor Patrick Minford, blogger Iain Dale (who resigned in the same year) and two local councillors. Liam Fox, the shadow defence secretary, was a member of the YBF's parliamentary council. Conor Burns was until shortly before becoming an MP in 2010 the vice-president of YBF.
Links: a. Iain Dale b. Collegiate Network c. TaxPayers' Alliance d. Conor Burns
Output:
c