The Oxford Comma (AKA the serial comma)

Which is correct? Ethical hacking is also known as penetration testing, intrusion _________________. a. testing, and red teaming b. testing and red teaming

Answer: a. or b., depending on guidelines followed.

Explanation:
A comma before a conjunction is sometimes called the Oxford comma or the serial comma. According to AP style, the Oxford comma should only be used when required for clarity, not in a simple list.

AskOxford explains the derivation of the Oxford comma. They say it’s optional — well, they would, wouldn’t they.

One of the most common arguments in favor of the Oxford comma is that leaving it out can sometimes cause ambiguity but including it will never impair meaning.

If your writing is supposed to follow any standard guideline, check to see what the rule is. Otherwise, whether you use the Oxford comma or not, the important thing is to be consistent.