Choose the biconditional that is equivalent to the definition, "a skyscraper is a very tall building."

Since this is a definition, it works both ways.

"If it is a very tall building, then it is a skyscraper."
"If it is a skyscraper, then it is a very tall building."

Put them together into a biconditional format.

"It is a skyscraper if and only if it is a very tall building."

Or

"It is a very tall building if and only if it is a skyscraper."

Either one would work.

Hope this helps!