Final answer:
The material of choice for a universal matrix band is steel, due to its strength, rigidity, and ability to be sterilized without deterioration.
Step-by-step explanation:
The material of choice for a universal matrix band is b) Steel. A universal matrix band is an important tool in restorative dentistry used to form the correct shape of a tooth when filling a cavity or performing other restorative procedures. Steel is chosen for its strength and rigidity, which are essential qualities to withstand the pressure during the condensation of the restorative material. It is also malleable enough to be adapted to the shape of the tooth, and it can be sterilized without deteriorating, which is crucial for reuse and maintaining dental hygiene standards.