The pliable and nimble antelope sped across the open grassland.

In this sentence, why would lithe be a better synonym for "flexible" than pliable is?
Lithe can also refer to graceful movement.
Lithe implies greater flexibility than pliable does.
Lithe can refer to mental flexibility as well as physical agility.

The best reason why "lithe" would be a better synonym for "flexible" than "pliable" is that lithe implies greater flexibility than pliable does. While pliable suggests the ability to bend or be molded easily, lithe implies a greater range of flexibility and agility, especially when it comes to physical movements. Additionally, lithe can also refer to graceful and nimble movement, which further emphasizes the idea of flexibility in a broader sense. Therefore, both the connotation of greater flexibility and the inclusion of graceful movement make "lithe" a better synonym in this context than "pliable."