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: Who won the race where Surtees qualified 15th? Passage:Surtees was formed by John Surtees after he left BRM to start his own team. He bought a McLaren M7C so that he could use it until the TS7 was ready. The car made its debut at the 1970 British Grand Prix with Surtees driving. He qualified 19th and retired with an oil pressure failure. In Germany, Surtees qualified 15th and was classified in ninth, although his race ended in an engine failure. The Austrian Grand Prix saw Surtees qualify 12th and retire when his engine blew. In Italy, the Englishman qualified 10th and retired when an electrical failure stalled the car at the start. The Canadian Grand Prix saw Surtees qualify and finish fifth. The team owner was joined by Derek Bell as a driver for the United States Grand Prix. Surtees qualified eighth and Bell 13th. The 1964 World Champion retired when his engine blew and Bell finished sixth. In Mexico, the team only entered Surtees. He qualified 15th and finished eighth.
Links: a. 1970 United States Grand Prix b. 1970 German Grand Prix c. 1970 Italian Grand Prix d. 1970 Mexican Grand Prix
Output:
b