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 many copies of Parkinson's Law have been sold in the United States? Passage:Parkinson divorced in 1952 and he married the writer and journalist Ann Fry (1921–1983), with whom he had two sons and a daughter. In 1958, while still in Singapore, he published his most famous work, Parkinson's Law, which expanded upon a humorous article that he had published in the Economist magazine in November 1955, satirising government bureaucracies. The 120-page book of short studies, published in the United States and then in Britain, was illustrated by Osbert Lancaster and became an instant best seller. It explained the inevitability of bureaucratic expansion, arguing that 'work expands to fill the time available for its completion'. Typical of his satire and cynical humour, it included a discourse on Parkinson's Law of Triviality (debates about expenses for a nuclear plant, a bicycle shed, and refreshments), a note on why driving on the left side of the road (see road transport) is natural, and suggested that the Royal Navy would eventually have more admirals than ships. After serving as visiting professor at Harvard University in 1958, the University of Illinois and the University of California, Berkeley in 1959–60, he resigned his post in Singapore to become an independent writer. To avoid high taxation in Britain, he moved to the Channel Islands and settled at St Martin's, Guernsey, where he purchased Les Caches Hall and later restored Annesville Manor. His writings from this period included a series of historical novels featuring a fictional naval officer from Guernsey, Richard Delancey, during the Napoleonic era.
 Links: a. Osbert Lancaster b. Parkinson's law c. Napoleonic era d. Parkinson's law
Output:
b