The Open Era in tennis, in which professionals were allowed to play the Grand Slams alongside amateurs, began in which year?

The correct answer is B, 1968. Until that year the Majors were reserved for amateurs, and the best players of the day, once they turned professional, could no longer enter them. In 1968 the tournaments were opened to all players, and every season from then on is called the Open Era, which is why the Australian Championships became the Australian Open and the French Championships the French Open.

Option A, 1958, is a decade too early and belongs to the period when the amateur rule was still being argued over. Option C, 1977, is the year of the Wimbledon centenary, a hundred years after 1877, which makes it a plausible looking but wrong choice. Option D, 1988, is the year Steffi Graf completed the Golden Slam and also the year tennis returned to the Olympic Games as a full medal sport at Seoul, so it appears in several tennis questions, just not in this one.