Question

the golgi apparatus is composed of flattened sacs referred to as options: tubules, cisternae, filaments, transitional vesicles

Explanation:

The Golgi apparatus is composed of flattened sacs called cisternae. Tubules are also part - of its structure but the flattened sacs are cisternae. Filaments are not the name for these flattened sacs. Transitional vesicles are involved in transport to and from the Golgi but not what the flattened sacs are called.

Answer:

cisternae