阅读下列短文，从每题所给的A、B、C和D四个选项中，选出最佳选项。
A
Mother Teresa (August 26, 1910～September 5, 1997) was a great woman, who did a lot to improve the social condition of mankind. Due to her contribution in serving the society, she was awarded the Nobel Peace Prize aged 69.
She was brought up in a Catholic family. When she was only seven, she lost her father. Even as a young child, she was interested in the life of missionaries (传教士). At the age of 18, she decided that she would become a nun. She left her home and went to join the Sisters of Loreto. It was the first step that she made towards providing services for mankind.
On the 7th of October in the year 1950, Mother Teresa received Vatican permission to start the Missionaries of Charity in Calcutta, the mission of which would be to take care of the needy, the homeless, and people who were shunned by the society. Then it had a number of branches all over the country. The journey of Mother Teresa's Missionaries of Charity started with the setting up of homes for “the Dying”．
In the year 1983, Mother Teresa suffered from a serious heart attack, while she was in Rome. However, she recovered. But, later in 1989, she again got an attack. Her health went worse and in the year 1991, she suffered from pneumonia. Taking her health problems into consideration, Mother Teresa decided to resign (辞职) from the post of head of the order.
A secret vote was conducted in which all the nuns voted for the stay of Mother Teresa except herself. So, she agreed to continue serving as head of the Missionaries of Charity. Day by day her health was getting worse. On September 5, 1997, exactly nine days after her 87th birthday, this great soul departed for heaven.
21．Why did Mother Teresa devote her life to the religious life?
A．Because her parents had a deep influence on her.
B．Because she wanted to provide services for others.
C．Because she thought the life of missionaries simple.
D．Because she came to know the Sisters of Loreto.
22．Which of the following words can replace the underlined word “shunned” ?
A．Cared. B．Concerned. C．Ignored. D．Affected.
23．Why did Mother Teresa decide to resign from her post?
A．She realized she couldn't fully serve the people in need.
B．She was only worried about her health condition.
C．She wished to lead a more comfortable life.
D．She knew a heart attack would take her life away at any time.
