Final answer:
Wimbledon is the only tennis major still played on grass, maintaining a tradition since its start in 1877 unlike other Grand Slams that use hard courts or clay.
Step-by-step explanation:
The only tennis major still played on grass is c) Wimbledon. Wimbledon, officially known as The Championships, Wimbledon, is one of the four Grand Slam tennis tournaments and is the oldest tennis tournament in the world. Unlike The Australian Open, which is played on hard courts, The US Open, also on hard courts, and The French Open, which is played on clay, Wimbledon has retained grass as its playing surface since its inception in 1877.