Answer:
a. Tetrapods were no longer tied to the water for reproduction
Step-by-step explanation:
The amniotic egg is hard-shelled and is called an amniotic egg because the embro develops within a sac called amnion.
Amphibians were first tetrapods to invade the land. The need to return to water for reproduction limited their distribution. Amniotes evolved an egg that broke the tie to freshwater.
Amniotic egg contains a series of extraembryonic membranes (Amnion, allantois, chorion, yolk sac) that, among their features , takes the aquatic environment with the egg.
Hence a. Tetrapods were no longer tied to the water for reproductionis believed to be the most significant result of the evolution of the amniotic egg.