In vb . . . . . . . . is the extension to represent project file.

The correct answer is: B. .vbp

A project file is a file that contains information about a Visual Basic project. It includes the names of the modules, forms, and other files that make up the project, as well as information about the project’s settings.

The extension .vbp is used for Visual Basic project files.

Option A, .frm, is the extension for a Visual Basic form file.

Option C, .cls, is the extension for a Visual Basic class file.

Option D, .vb, is the extension for a Visual Basic source code file.