Imposing layered system constraints in REST

The requirement for a layered system is considered as a fundamental principle in REST.

In the context of the REST architecture, which of these architectural benefits are attained by imposing layered system constraints?

Options

1. Placing a bound on overall system complexity
2. Promotion of substrate independence
3. Interface uniformity
4. Only Choice 1 and Choice 2
5. Only Choice 2 and Choice 3