System Analysis and Design: Per the given scenario, I have to choose between (1) Use Case Diagram (2) Activity Diagram (3) Class Diagram. Which diagram is correct for better communicating this specific scenario?

Scenario 2:

SalesPower, an online customer relations management provider (kind of like SalesForce) is causing Marcus headaches. As the CIO of ReallyBigGlobalCorp, Marcus needs to understand the implications of using SalesPower to his organization. Unfortunately there are so many different stakeholders who can interact through SalesPower that he is becoming confused. For example:

Suppliers - Suppliers can interact with SalesPower by conducting all transactions with ReallyBigGlobalCorp (RBGC). This includes all value chain activities needed to perform inbound logistics (meaning that infrastructure, human resources, technology, and procurement activities are all executable through SalesPower).

Customers - Individual customers can interact with SalesPower. Not only can customers customize their purchases through SalesPower, but customers can ask for second party services that SalesPower links to (think how GeekSquad would build and install a product) or services that ReallyBigGlobalCorp (RBGC) would provide. Finally Customers can track their orders through a third party provider add-in to SalesPower.

Third parties - SalesPower links in third party organizations that add value to the primary activities of ReallyBigGlobalCorp. SalesPower also gives RBGC the ability to limit which third parties can interact with their sales and service processes.

How can Marcus think about these stakeholders and the activities the stakeholders can perform? Can you help Marcus wrap his head around them? (This is a business one!)