In the passage, "Angel of the Battlefield", which of the following is the MAIN IDEA of the passage?
A. Clara Barton was inspired by her experiences caring for others to establish the American Red Cross.
B. Clara Barton placed a magazine ad requesting much-needed supplies for Civil War soldiers.
C. When she was a young girl, Clara Barton cared for her sick brother and nursed him back to health.
D. The American Red Cross was established in 1881 and continues to serve many people today.