A dodecahedron is a three-dimensional geometric shape that has 12 faces. Each face of a dodecahedron is a regular polygon, which means that all its sides and angles are equal. In this case, the regular polygons that make up the faces of a dodecahedron are pentagons.

The answer to this question is option 'B', which states that a dodecahedron has 12 regular pentagons. This can be explained further as follows:

A dodecahedron
A dodecahedron is a polyhedron with 12 faces, 20 vertices, and 30 edges. It is one of the five platonic solids, which are regular convex polyhedra. In a dodecahedron, each face is a regular polygon, and the same number of polygons meet at each vertex.

Regular polygons
A regular polygon is a polygon in which all sides and angles are equal. For example, a regular triangle is an equilateral triangle, a regular square is a square, and a regular pentagon is a pentagon with equal sides and angles.

Dodecahedron faces
In the case of a dodecahedron, each face is a regular pentagon. This means that all the sides and angles of each pentagon are equal. Since a dodecahedron has 12 faces, there are 12 regular pentagons that make up the surface of the dodecahedron.

Other options
The other options in the question are not correct. A dodecahedron does not have equilateral triangles as its faces because the sides and angles of an equilateral triangle are not equal to those of a regular pentagon. Similarly, a dodecahedron does not have squares or rectangles as its faces because these shapes do not have equal sides and angles.

Conclusion
In conclusion, a dodecahedron has 12 regular pentagons as its faces. Each pentagon has equal sides and angles, making it a regular polygon. The other options in the question (equilateral triangles, squares, and rectangles) are not correct as they do not have equal sides and angles.