Answer:
We know that the relation between the sound of a word and its meaning is arbitrary because:
A. Different languages have different words that refer to the same objects/concepts.
Step-by-step explanation:
There are two reasons for this answer. First, only cognates work as a kind of synonym because they come from the same origin. Second, the majority of languages don't share the same origin, rules, inspirations, and applications. Therefore different words refer to the same objects. An example is red, Rojo, aka. All of them mean red.