急问THEREFORE的用法

请问THEREFORE是否不能充当两个句子的连接词？？

以大全987-206为例

1.        Charles Lindbergh, for his attempt at a solo transatlantic flight, was very reluctant to have any extra weight on his plane, he therefore refused to carry even a pound of mail, despite being offered $1,000 to do so.

(A) Charles Lindbergh, for his attempt at a solo transatlantic flight, was very reluctant to have any extra weight on his plane, he therefore

(B) When Charles Lindbergh was attempting his solo transatlantic flight, being very reluctant to have any extra weight on his plane, he

(C) Since he was very reluctant to carry any extra weight on his plane when he was attempting his solo transatlantic flight, so Charles Lindbergh

(D) Being very reluctant to carry any extra weight on his plane when he attempted his solo transatlantic flight was the reason that Charles Lindbergh（E）

(E) Very reluctant to have any extra weight on his plane when he attempted his solo transatlantic flight, Charles Lindbergh

此句中的therefore不能充当连词吗？请指教～～

能否接句子要看词性是否是连词，therefore是副词，所以不能连接句子。

我怎么觉得这题在OG上见过呀,但是没找着，正确答案是什么？

thx carolhide~