a. Use Case Diagram

The Use Case Diagram will involve the main actors interacting with the system: Donor, Volunteer, and Admin.

Here's an outline of the use cases:

• Donor: Register/Login, Make Donation, View Donation History.

• Volunteer: Register/Login, Select Event, View Schedule.

• Admin: Approve Donations, Assign Volunteer Tasks, Create Donation Campaigns, View Reports.

You can draw this diagram using a tool like Lucidchart or draw.io.