Definition: 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.
Input: Question: How old was Robert Nairac when Jones was promoted to lieutenant? Passage:He was promoted to lieutenant on 23 January 1962, captain on 23 July 1966, and major on 31 December 1972, At this time he was brigade major at HQ 3rd Infantry Brigade in Northern Ireland. As such he was responsible for the efforts to find Captain Robert Nairac who had been abducted by the Provisional IRA. Nairac and Jones had become friends and would sometimes go to the Jones household for supper. After a four-day search, the Garda Siochana confirmed that Nairac had been shot and killed in the Republic of Ireland after being smuggled over the border. On 13 December 1977 he was appointed a Member of the Order of the British Empire (MBE) for his services in Northern Ireland that year. On 30 June 1979 he was promoted lieutenant colonel, and on 1 December 1979, he was transferred to the Parachute Regiment. In the 1981 New Year Honours he was appointed an Officer of the Order of the British Empire (OBE).
Links: a. Provisional Irish Republican Army b. Robert Nairac c. First lieutenant d. Lieutenant colonel (United Kingdom)
Output:
b