When Jean Calment entered the world in 1875, telephones and automobiles still lay in the future. Albert Einstein and Pablo Picasso were not yet born. The Eiffel Tower was 14 years from being built. As a teenager, she met Vincent Van Gogh, near her home in Arles, in the south of France. He was "very ugly, ungracious, impolite, sick--I forgive him, they called him loco." She recalled. When she died last week at age 122, she was the world's oldest person. (There were others who claimed to the title, but only Calment had the official documents to prove her age) Each February 21, her birthday, she would share the secrets of long life. Some years it was "a sense of humor", others it was "keeping busy". "God may have forgotten me," she once explained. The truth probably was that she had good genes. Her mother reportedly lived to be 86 and her father 94. Her life had its sadness: she outlived her husband, her only daughter and her grandson. According to a friend, she was _ "If you can't do anything about it," she reportedly said, "don't worry about it." In her last years she was nearly blind and deaf, but her health remained good. She ate a few bars of chocolate each week and continued smoking until a few years ago, when she could no longer light her own cigarettes. She never lost her sense of humor. On her 110thbirthday, she commented, "I have only ever had one wrinkle, and I am sitting on it." Her longevity made her famous. Her spirits made her eternal The author believes that Calment's longevity is mainly due to   _  .
a sense of humor being kept busy belief in God good genes
Question: When Jean Calment entered the world in 1875, telephones and automobiles still lay in the future. Albert Einstein and Pablo Picasso were not yet born. The Eiffel Tower was 14 years from being built. As a teenager, she met Vincent Van Gogh, near her home in Arles, in the south of France. He was "very ugly, ungracious, impolite, sick--I forgive him, they called him loco." She recalled. When she died last week at age 122, she was the world's oldest person. (There were others who claimed to the title, but only Calment had the official documents to prove her age) Each February 21, her birthday, she would share the secrets of long life. Some years it was "a sense of humor", others it was "keeping busy". "God may have forgotten me," she once explained. The truth probably was that she had good genes. Her mother reportedly lived to be 86 and her father 94. Her life had its sadness: she outlived her husband, her only daughter and her grandson. According to a friend, she was _ "If you can't do anything about it," she reportedly said, "don't worry about it." In her last years she was nearly blind and deaf, but her health remained good. She ate a few bars of chocolate each week and continued smoking until a few years ago, when she could no longer light her own cigarettes. She never lost her sense of humor. On her 110thbirthday, she commented, "I have only ever had one wrinkle, and I am sitting on it." Her longevity made her famous. Her spirits made her eternal The author believes that Calment's longevity is mainly due to   _  .
A. a sense of humor
B. being kept busy
C. belief in God
D. good genes
Answer: