What type of PG binders are commonly found in friction courses?

The correct choice, which is PG 76-22 (PMA), is commonly found in friction courses due to its enhanced performance characteristics. This type of binder is modified with polymer additives, specifically polymer-modified asphalt (PMA), allowing it to better resist deformation, high temperatures, and fatigue cracking. Friction courses, which are typically the top layer of asphalt pavement, require a binder that not only provides good adhesion and durability but also improves the skid resistance of the surface for safety reasons.

PG 76-22 (PMA) has a higher temperature grade compared to standard binders, making it especially suitable for areas that experience extreme heat or heavy traffic loads, where enhanced performance in durability and resistance to wear is critical. This helps in maintaining the integrity of the surface and in providing a safe driving experience.

While other options might indicate suitable grades for different applications, they do not possess the same level of performance enhancement attributes that are critical for friction course applications.