Final answer:
The word 'wag' can be related to the concept of a 'swing'. Therefore, option a) swing is the word that matches 'wag' the most.
Step-by-step explanation:
The word 'wag' can be related to the concept of a 'swing'. In a swing, an object moves back and forth around a fixed point. Similarly, when something wags, it moves back and forth in a similar motion. Therefore, option a) swing is the word that matches 'wag' the most.