Choose the most appropriate option to fill in the blanks of the given sentence.
It’s ______ I’ve always admired and envied, across the species spectrum in the animal kingdom: the natural ______ with which creatures move in their ordinary lives.

Option B: Correct.

To answer the most appropriate fit for the sentence we have to first make sense of the sentence with blanks.

By reading the sentence we get an idea that- there is a certain quality about animal kingdom that the author envies and admires.

So we can get a sense through this conclusion that the quality being talked of should be a positive adjective.

The positive adjectives are only in option B- ease and grace.

Hence B is the right choice.