Final answer:
The answer to the student's question is A) Pablo Casals. He was paid tribute to by 100 cellists in 1970 when they played "Sardana" under his direction.
Step-by-step explanation:
The student's question is about a historical event that took place in 1970, where 100 cellists gathered to pay tribute to a master cellist by playing "Sardana". Among the options provided, the correct answer is A) Pablo Casals, who was a world-renowned cellist and conductor. At that time, Casals would have been an elderly man, and this tribute was a sign of respect and admiration from other accomplished cellists.
The piece "Sardana" is also associated with Catalan folk music, and Pablo Casals was from Catalonia, which is another indication that he is the master cellist being referred to. Yo-Yo Ma, Mstislav Rostropovich, and Jacqueline du Pré are also famous cellists, but the event described specifically pertains to Pablo Casals.