Final answer:
The evolution of the earliest tetrapods was marked by the development of feet with digits, which facilitated terrestrial movement and was a significant step towards the diversity of land-dwelling vertebrates we see today. The correct option is 3) feet with digits
Step-by-step explanation:
A trend in the evolution of the earliest tetrapods was the development of feet with digits. These ancestral vertebrates, such as Ichthyostega and Acanthostega, evolved from fish-like ancestors and began to exhibit features more suited for life on land.
The appearance of feet with digits was a significant adaptation, allowing these organisms to navigate land environments better than their finned predecessors.
Although they retained aquatic characteristics such as possibly having gills, their limbs resembled those of modern tetrapods, including amphibians.
These early tetrapods were crucial in paving the way for further evolution into diverse land-dwelling vertebrates, including reptiles, birds, and mammals. The correct option is 3) feet with digits