Final answer:
The outer zone in the theory of protection refers to areas with the least restrictive access and is best described as public access areas.
Step-by-step explanation:
The outer zone in the theory of protection, sometimes related to urban planning or security strategies, refers to areas that are open to public access. This notion aligns with the concept depicted in the adapted version of Burgess' Concentric Ring Model, where the outer zones, such as the suburbs and exurbs, tend to have less restrictive access compared to inner, more secured areas. Therefore, among the given options, the correct answer to describe the outer zone in the theory of protection is Option 2: Public access areas. The other zones - the most secure area, semi-restricted areas, and no access areas - typically correspond to areas closer to the center of the model or specialized zones with particular security requirements.