Frida Kahlo was born on July 6, 1907, in Mexico City. Kahlo began painting after she was severely injured in a bus accident in 1925. Today, she is considered one of Mexico's greatest artists. Kahlo grew up in the home where she was born, later known as the Blue House or Casa Azul. Her father, Guillermo, was a photographer who had emigrated from Germany to Mexico, where he met and married her mother, Matilde. She had two older sisters, Matilde and Adriana. Her younger sister, Cristina, was born the year after Frida. At age 6, Frida contracted polio, which confined her to bed for 9 months. Upon recovery, she limped when she walked because of damage to her right leg and foot. Her father encouraged her to take up soccer, swimming, and even wrestling, highly unusual activities for a girl at the time, to help aid in her recovery. On September 17, 1925, Kahlo was traveling on a bus that collided with a streetcar. She sustained serious injuries in the accident, including a broken spine, collarbone, ribs, and pelvis. She stayed at the Red Cross Hospital in Mexico City for several weeks, then returned home to recover. She began painting during her recuperation and finished her self-portrait the following year. Her parents supported her artwork: her mother had an easel made that Kahlo could use while in bed, and her father gave her a box of oil paints and brushes. In 1938, Kahlo had her first solo art exhibition in New York City. As an adult, Kahlo became politically active, joining the Young Communist League and the Mexican Communist Party. She and her husband, the painter Diego Rivera, befriended Leon Trotsky in 1937 after he fled to Mexico for political asylum from the Soviet Union. In which of the following sources would a reader most likely find this passage?