题目内容：
根据材料请回答British Columbia is the third largest Canadian province, both in area and population.It is nearly one and a half times as large as Texas, and extends 800 miles (1,280 km)north from the United States border. 46 .
Most of British Columbia is mountainous, with long, rugged ranges running north
and south. 47 .During the last Ice Age, this range was scoured (侵蚀) by glaciers(冰川) until most of it was beneath the sea.Its peaks now show as islands scattered alongthe coast.
The southwestern coastal region has a humid mild marine climate.Sea winds that blow inland from the west are warmed by a current of warm water that flows through the Pacific Ocean, As a result, winter temperatures average above freezing and summers are mild. 48 .
49 .As they rise to-cross the mountains, the winds are cooled, and their moisture begins to fall as rain.On some of the western slopes almost 200 inches (500 cm)of rain fall each year.
Morethan half of British Columbia is heavily forested. 50 .These forest giants often grow to be as much.as 300 feet (90m) tall, with diameters upto 10 feet (3m).More lumber is produced from these trees than from any other kind of tree in North America.
A.On mountain slopes that receive plentiful rainfall, huge Douglas firs (洋松) rise in towering columns
B.It includes Canada's entire west coast and the islands just off the coast
C.These warm western winds also carry moisture from the ocean
D.Plants are the basis of the food pyramid for all living things, even for other plants
E.Even the coastal islands are the remains of a mountain range that existed thou-sands of years ago
F.Inland from the coast, the winds from the Pacific meet the mountain barriers of the coastal ranges and the Rocky Mountains
请选择（46）处的最佳答案
参考答案：
答案解析：