What serves as reinforcement for asphalt shingles?

The mat serves as reinforcement for asphalt shingles primarily because it provides structural strength and stability to the shingles. Typically made from fiberglass or organic materials, the mat is sandwiched between layers of asphalt and granules. This layer is crucial because it not only adds durability but also helps the shingles resist tearing and prevent damage from various weather conditions.

While the base layer and granules are important components of asphalt shingles, they do not function primarily as reinforcement. The base layer refers to the underlying roof structure that supports the shingles, and the granules are primarily protective and aesthetic, serving to shield the asphalt from UV damage and to enhance the appearance of the roof. Sealant, on the other hand, is used to bond shingles together and to provide waterproofing but does not contribute to the structural reinforcement in the same way the mat does.

Overall, the mat plays a vital role in the overall performance and longevity of asphalt shingles, making it the correct answer in this context.