参考答案：A

解析：

这是一个测试从属连词的试题，even though作“即使……也要……”阱，表示让步。如：Even though it is difficult, I’ll do it. 即使很难，我也要做。even though也可以换成even if，如：Even if we achieve great success in our work, we should remain modest. 即使我们的工作取得了很大成绩，我们也应该戒骄戒躁。just because作“正是因为”讲，now that作“既然……”讲，表示原因，前者比后者强调原因的语气强些。例如：You mustn’t suppose that she is satisfied just because she doesn’t complain. 你千万不要认为她不抱怨就是满意丁。Now that you’ve mentioned it, I do remember what he said yesterday.既然你提到了，我确实想起了他昨天说的事。as though也可换成as if，作“好像，似乎”讲，有时从句中谓语动词用虚拟形式。如：You talked as though (if) you were the boss. 你说起话来好像你就是老板。It looks as if (though) it were going to rain. 看上去好像要下雨。本句前后两部分是转折语气，因此应选even though，其他几项在语义上均不通。