Comma or no comma before 'and'?

[Tansy]

Re: Module 1 Self Assessment Group b
Article 6-10: Each of the 5 sentences, by the look of it, is either a run-on sentence or a non-run-on sentence.

Article 7. I could go to only a few websites and I did not have an email address, so it was very hard to sign up for the online course.
^
This is not a run-on sentence. However, some textbooks say you should put a 'comma' in front of 'and', but other textbooks say you can either put a 'comma' in front of 'and' or you can omit the 'comma'.

If I say Article 7. is wrong, I'll be in trouble with error identification in this group--the error type doesn't belong to this group.
On the other hand, if I say Article 7. is correct, I might choose the wrong answer in the written exam.

So, can you please tell me which rule STOU teachers go by?

[Jaraswat]

Item 7 of Section B is already a correct sentence. You're right. In this sentence, you can also add a comma in front of 'and' if you wish. The sentence will still be correct.

[Tansy]

Thank you, teacher.