I understand how we eliminated B based off biting in outside information but couldn't we also just have eliminated B by pointing to the author's concession point where it says killer whales tend to not behave differently around these boat noises so essentially not making it either more likely or less likely for them to communicate

I'll just use a random example about first responders again to clarify my reasoning and I hope if I'm wrong someone can guide me

Superset - Professional Basketball Player

Subset - NBA Player

If you are an NBA Player it's Sufficient but not necessary to be considered a professional baseball player

But it is necessary that you are Professional Basketball player to be part of the NBA but it's not sufficient