Two-tier and three-tier client-server architecture

Which layer is responsible for handling data processing in the Three-Tier architecture?
What is the primary advantage of using a Three-Tier architecture over a Two-Tier architecture?
In a Three-Tier architecture, which layer is responsible for interacting with the database?
Which of the following technologies is typically used for the Application layer in a Three-Tier architecture?
A receiver using stop-and-wait ARQ sends ACK framed numbered __________.