Q22

[AndreaO452]

Can someone please show me why O is not listed?

[Misti Duvall]

Can someone please show me why O is not listed?

Sure! The short answer is because it doesn't have to be. That's because of what the question is asking: it's not asking for a list of all possible elements that could be in the middle group. It's asking what could be one possible list of elements. So you don't need to have every single element that could be in the middle, just one list of elements that works.

For example:

I have three kinds of ice cream: vanilla, chocolate, and strawberry. What's a list of all the flavors of ice cream I could eat? Vanilla, chocolate, and strawberry. But what's one possible list of the ice cream flavors I actually eat? Chocolate and strawberry.

Hope this helps.