I am developing a credit card applicatoin in C# (.Internet Framework v3.5) and I have to store some tables with associations between these questions database.

An amount a great database system to incorporate in my application and why?

Important: I'm not going my client to set up a server (like MySQL or SQL Server), unless of course it's installed with .Internet Framework v3.5.

I've been considering SQLite and Microsoft Access because both keep database inside a file rather than a server, but I am just wondering if you will find every other options I've. For instance, only for testing purpose, I patterned my database using Entity Framework and that i saved it inside a .mdf file, and labored fine, but I am not necessarily confident that SQL Server is needed to questionOralterOrplace info into that .mdf file?

SQL Server CE (compact edition) does not require any installation, you need to simply deploy the right DLL together with your application. The database is saved inside a file, no server is required.

SQLite and SQL Server CE both offer the Entity Framework (use this connector for SQLite)

To be sure that SQLite is a great choice. It is a effective, broadly used (Opera, Mac OS, Google Gears, take your pick) database in a tiny package. It's within the public domain, and there is a handy .NET binding together with a ADO.Internet provider. I have tried on the extender myself inside a WinForms application.