My app marked that answer as acceptable

Agreed, this should be added as an acceptable translation.

I answered so too (;_;)

Did you try it? That was my correct answer.

It has been added - that's what i put and it was correct

Agreed

It means so. Unlike English where you'd use either because or so, it's common in Chinese to say because x, so y

Because ...., So ...... . 因为…，所以…。

It's equivalent to "so" or "therefore" - "[Because] he is a teacher, therefore/so he is at school" would be a more literal translation of the "correct" answer

So

Therefore

It's like "that's why"

Or "So"

This is actually a good translation too.

Because of the range of different ways this question can be presented, it's not clear what you are saying is wrong. Your version is possible, but the English version without 'the' that I got is presented with is much more natural.

Agreed. The second "ta" is redundant