Gazelle : swift::

To figure out a similar pair, we first need to understand the pair already present.

A gazelle is an animal that has swift, graceful movements. The relationship is between an animal and a positive adjective for its movements.

Similarly, a swan is an animal whose movements are described as graceful.

Why not others:

Horse: slow- a horse is not an animal with slow movements

Lamb: bleat- lamb makes a bleating sound, bleating is not about the lamb's movement

Lion: roar- roar is the sound the lion makes, not the movement,