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.
Input: Question: How old was the commander in chief when he coordinated a massive anti-guerrilla operation? Passage:In 1970, 22-year-old Crespo had dropped out of IST and was eventually drafted into military service in the Portuguese Colonial War. He transferred to Mozambique where his military occupation was to check the cement cargoes from Beira to the Cahora Bassa Dam construction site, near Tete. Some time later, due to his good fluency in English, he was placed in the press office of Kaúlza de Arriaga, the commander in chief of the Portuguese Armed Forces in Mozambique, who had coordinated a massive anti-guerrilla operation against FRELIMO separatists in 1970 - the Gordian Knot Operation. While serving in the army, Crespo also entered the newly created School of Medicine of the University of Lourenço Marques where he would complete a number of academic disciplines but did not graduate. He also married Helen de Souza from Johannesburg, a South African woman with Portuguese ancestry who worked in genetics. After the Carnation Revolution left-leaning military coup at Lisbon in April 1974, fresh out of the troop, Crespo fled Mozambique for South Africa.
 Links: a. Portuguese Colonial War b. Tete, Mozambique c. Kaúlza de Arriaga d. Kaúlza de Arriaga
Output:
c