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: Who was in charge of the CIA the year Fanon went back to the US for cancer treatment? Passage:Upon his return to Tunis, after his exhausting trip across the Sahara to open a Third Front, Fanon was diagnosed with leukemia. He went to the Soviet Union for treatment and experienced some remission of his illness. When he came back to Tunis once again, he dictated his testament The Wretched of the Earth. When he was not confined to his bed, he delivered lectures to Armee de Liberation Nationale (ALN) officers at Ghardimao on the Algero-Tunisian border. He made a final visit to Sartre in Rome. In 1961, the CIA arranged a trip to the U.S. for further leukemia treatment at a National Institutes of Health facility. During his time in the United States, Fanon was handled by CIA agent Oliver Iselin.
Links: a. Central Intelligence Agency b. National Institutes of Health c. Sahara d. Tunis
A:
a