Laos has a land area about the same as Great Britain but only four million in population, where many are members of hill tribes ensconced in the virtually inaccessible mountain valleys of the north.

about the same as Great Britain but only four  million in population, where many

of about the same size as Great Britain is, but in Laos there is a population of only four million, and many

that is about the same size as Great Britain's land area, but in Laos with a population of only four million people, many of them

comparable to the size of Great Britain, but only four million in population, and many

comparable to that of Great Britain but a population of only four million people, many of whom

考题讲解

A选项：比较对象不正确，应该比较的是英国的面积而不是英国本身，即，应改为：
Laos has a land area about the same as that of Great Britain

B选项：本选项中Laos是there is a population of only four million的地点状语。其描述的是“在老挝里，这仅有400w人口”，这是不合逻辑的，例如：
(1) 在中国，这有一辆车。（In China, there is a car.）
(2) 中国有一辆车。（China has a car）

C选项：Laos不是拥有population of only four million的主语错误同(B)。

D选项：
“老挝有多少人口”和“这些人口的分布情况”并列错误同(B)。

E选项：
Correct. 本选项在语法和逻辑上均是正确的。