Which building block of business model canvas addresses the customer's willingness to pay?

Revenue Streams define how a company makes money from each customer segment, detailing the pricing mechanisms and methods through which customers are willing to pay for the value proposition. This directly addresses the customer's willingness to pay for products or services.

Cost Structure identifies all the costs incurred to operate a business model, focusing on expenses, not customer willingness to pay.

Customer Segments defines the different groups of people or organizations an enterprise aims to reach and serve, focusing on who the customers are, not how they pay.

Customer Channels describe how a company communicates with and reaches its customer segments to deliver a value proposition, focusing on delivery mechanisms, not payment willingness.