The correct answer is D. all of the mentioned.
In a layered architecture, each layer is responsible for a specific set of tasks and is only allowed to interact with the layers immediately above and below it. This helps to keep the layers loosely coupled, which makes the system more modular and easier to maintain.
Option A is correct because the layers are not strongly coupled to the layers above them. This is because each layer is only allowed to interact with the layers immediately above and below it.
Option B is also correct because each layer is strongly coupled only to the layer immediately below it. This is because each layer needs to be able to communicate with the layer below it in order to perform its tasks.
Option C is also correct because overall layered-style architectures are loosely coupled. This is because the layers are only allowed to interact with the layers immediately above and below them, which helps to keep the system modular and easy to maintain.