World War II lasted from 1939 to 1945. Life changed for everybody, including women and children because of the war. Millions of people lost their lives during the war. The Diary of a Young Girl was a record of that time. The book was written by a girl named Anne Frank. Anne Frank was born in Germany in June 1929. Because the German Nazi  hated the Jews  and warned to kill them, her family had to move to another country. In July 1942, they went into hiding in a secret place in her father's office. During that difficult time, Anne kept writing diaries until she and her family were discovered by the Nazis in August 1944. They were caught and sent to a Nazi camp. The next year, her mother died. In the same year, she and her elder sister died of illness, before the war ended. After the war, her father collected her diaries and the book The Diary of a Young Girl came out in 1947. It has been put into over 30 languages since then. The book has been read by people all over the world. In her diary, Anne wrote down her thoughts, her feelings, her hopes and her dreams for the future, "I want the diary to be my friend, and I'm going to call this friend Kitty." "I can't spend all day complaining because it's impossible to have any fun! ... Every day, I feel the beauty of nature and the goodness of the people around me. With all that, why should 1 be sad?" The Diary of a Young Girl has also become a symbol of the greatness of the human spirit. It is called one of the wisest and most moving records on war. According to the passage, "Kitty" is   _  .
her diary her elder sister her mother her hiding place