Which of the following word pairs illustrates synonyms?

The word pair "Eager/Enthusiastic" illustrates synonyms, as both terms convey a similar meaning related to having a strong desire or interest in doing something. When someone is eager, they are typically excited and ready to engage or participate, while enthusiastic denotes a high level of interest and passion. Thus, in various contexts, these words can be used interchangeably, highlighting their synonymous relationship.

In contrast, the other pairs do not represent synonyms. For instance, "Agree/Disagree" are opposites, where one indicates concurrence while the other indicates dissent. "Above/Below" also represent opposing concepts in terms of spatial relationships, with one word signifying a higher location and the other a lower one. Similarly, "Happy/Sad" are antonyms, as they describe opposite emotional states. Therefore, "Eager/Enthusiastic" is the only pair that accurately represents the concept of synonyms.