On further reflection, that sentence (option D) doesn’t appear to break any rules of English grammar — let’s see what other teachers have to say. Nevertheless, we usually don’t start a sentence with “because”, so that sentence just doesn’t “sound” as good as option A. It would sound more natural (if unnecessarily verbose) to say, “It is because Zhou Lan… that her English is so good”, or perhaps, “It’s because of the fact that Zhou Lan… that her English is so good”. If we wanted to use a conjunction at the very beginning, we could use a different one instead, for example, “As (or “since”) Zhou Lan often talks to her friends in English, her English is very good”.

Choose A, "Zhou Lan often talks to her friends in English, so her English is very good". Choice D looks more like Chinese :)

A

Both ok to me. There is this nonsense rule that you can’t start a sentence with ‘because’. That is only true if you are completing the previous sentence.

a吧 没怎么见过because开头的句子 because of开头的倒见过 一般连词在两个句子中间