Helen Keller lost her sight and hearing at the age of two because of an illness. Since she was deaf, she also lost the ability to speak, for we learn by imitating what we hear. At first, it seemed impossible that she would ever understand others or be understood by them. Hers was thus a very lonely world. She was helped by an excellent teacher called Miss Sullivan, who had been blind as a child but recovered her sight after an operation. Miss Sullivan volunteered to help Helen and taught her to speak, read and write. Helen later went to a university and even gained a degree. She then spent the rest of her life working to help the blind and the deaf.

Choose the correct option to answer each question.

Why did Miss Sullivan volunteer to help Helen?