Which of the following is an example of an acceptable time to ignore the rules and etiquette of a sport?

I guess when they go against your morals and values you hold as an individual. If they do (go against them, negatively) then you should not play the sport

Explanation:

"I guess when they go against your morals and values you hold as an individual"

If you feel uncomfortable or hurt in a way that changes how you think of that sport (negatively) then stop it right then and there

But there is...

When... let's say people are known in the sport for being mean to each other and the other team

That is when you step up and be the bigger person and do what's right, being nice and welcoming, "do unto others as you would like others do unto you"

if the other team is being mean...

then still be that good person but show that you mean business and play harder, use the anger or irritation that, that team is causing you to have and play your heart out, use it as a drive

"kill them with kindness"  

It's all about integrity and showing the best you

sadly i believe the answer is d