Quality is delighting customers
In 3 tier architecture there are 3 layers in the architecture. They are 1) Application(Presentation) layer 2)Business Logic Layer and 3)Data layer
In n tier architecture, Data layer is divided into 2 layers i.e Data access and Database.
In n tier architecture, Data access layer and Database layer may or may not reside on the same location.keeping that into consideration we have to prepare Test strategy and Test Approach.
D)Application testing : GUI, Functional, Adhoc, Compatibility, Security, Load,performance, stress...