The number of faces of a rectangular prism is 6.

A rectangular prism is a three-dimensional shape that has six faces, all of which are rectangles. Each face of the rectangular prism is a flat surface that is bounded by four straight edges. The faces of a rectangular prism are arranged in pairs, with each pair being congruent and parallel to each other.

Explanation:

To understand why a rectangular prism has 6 faces, let's break down the structure of a rectangular prism:

1. Front and Back Faces: The rectangular prism has two faces that are parallel to each other and are rectangular in shape. These faces are called the front and back faces of the prism.

2. Top and Bottom Faces: The rectangular prism also has two faces that are parallel to each other and are rectangular in shape. These faces are called the top and bottom faces of the prism.

3. Side Faces: The rectangular prism has two more faces that are parallel to each other and are rectangular in shape. These faces are called the side faces of the prism.

Thus, a rectangular prism has a total of 6 faces: 2 front and back faces, 2 top and bottom faces, and 2 side faces. Each face is a rectangle, and all the faces together enclose the solid shape of the rectangular prism.

In conclusion, the correct answer is option 'B' - 6. A rectangular prism has 6 faces.