What was the primary purpose of ziggurats?

Religious structures
Commercial buildings
Palaces
Defense

The primary purpose of ziggurats was religious.

The primary purpose of ziggurats was religious structures. They were temple-like towers built in ancient Mesopotamia with the intention of serving as platforms for the worship of deities.

The primary purpose of ziggurats was religious, as they were constructed as massive temple complexes in ancient Mesopotamia. To reach the answer, one can look into the historical context and characteristics of ziggurats.