Final answer:
The theatre time period that used masks, outdoor theatres, and religious-themed performances was Ancient Greek theatre.
Step-by-step explanation:
The theatre time period that used masks, outdoor theatres, and religious-themed performances was Ancient Greek theatre. This period is renowned for its use of masks to transform actors and convey different roles, the architectural marvel of open-air theatres built into hillsides that promoted natural acoustics, and the strong link between religious themes, particularly Dionysian rituals, and theatrical expression.
Such practices reflect the deep cultural significance of theatre in Ancient Greek society, where plays were not only a source of entertainment but also a way of exploring human nature, morality, and the gods.