The original Olympics took place nearly 3000 years ago in the year 776 BC. Many different sports were played, including boxing, running, throwing the discuss , though there were fewer sports involved than those in the modern Olympics. The Games were held every five years until they were forbidden by the Romans in AD 393. The first new Olympics were held in 1896 in Greece. From 1900, the Games were held every four years, only three Olympics were wiped out because of wars---1916, 1940 and 1944. Nowadays, different countries hold the Games in turns. The country which holds the Games provides vast facilities, including a stadium , swimming pools and accommodation , but competing countries pay their own players' expense. The Olympics start with the arrival in the stadium of a torch , lighted on Mount Olympus by the sun's rays. The well-known Olympic flag, however, is a modern conception : the five interlocking  rings symbolize   the uniting of all five continents  that take part in the Games. What do the five interlocking rings symbolize?   _  .
Five continents Five players Five cities Five countries