'For' can be used exactly in the sense of 'because' but it is rather literary. Honestly,either could be the answer. 'Because' is the most natural choice. It is not usually preceded by a comma, suggesting it is not the correct answer here. However, the comma could be used to avoid ambiguity. 'For' is possible but is very rare in this sense and is only really used in very literary texts. However, this sentence does sound like it could come from such a text. To be honest, this is not a great question because, for various reasons, either is possible. Generally, use 'because' as a conjunction to introduce reasons. It is by far the most common and natural way to do it. 'For' can be used in this way but it is very rare. Think if it as something to understand rather than use.

"Little Wang Jun could not go to school, for his family was too poor" is technically correct, but that is much too formal/poetic for everyday, natural English. Using "for" sounds more like storytelling, but it is technically not wrong. However, if you were to use it in a conversation, it would be too formal and would not sound natural. In a normal conversation, you would use "because". Hope this helps!

Hi Jane. Actually, both is correct. But the answer may be "for" because you can omit the comma before "because".

In this case the answer is because rather than for. Because sounds natural and it is giving the reason behind the action. While for is more used as in for someone else. I wouldn’t really say for is a reason usually. Like who is that for?