阅读理解：请根据短文内容，为每题确定l个最佳选项。

The National Trust。

The National Trust in Britain plays an increasingly important part in the preservation for public enjoyment of the best that is left unspoiled of the British countryside. Although the Trust has received practical and moral support from the Government, it is not a rich government department. It is a voluntary association of people who care for the unspoiled countryside and historic buildings of Britain. It is a charity which depends for its existence on voluntary support from members of the public. Its primary duty is to protect places of great natural beauty and places of historical interest.

The attention of the public was the first drawn to the dangers threatening the great old houses and the castles of Britain by the death of the Lord Lothian, who left his great seventeenth-century house to the Trust together with the 4500-acre park and estate surrounding it. This gift attracted wide publicity
A. Government agency depending on voluntary services.
B. Non-profit organization depending on voluntary services.
C. Government department but is not rich.
D. Private organization supported by the government.