Which agency regulates fire alarm installations in Texas?

The Texas Department of Insurance is the correct choice because it oversees various aspects of fire safety regulations and insurance requirements related to fire alarm systems in the state. This agency is involved in ensuring that fire alarm installations comply with the statutory regulations and standards that ensure public safety and the effectiveness of fire protection systems.

The Texas Fire Marshal's Office plays a crucial role in fire safety, including establishing codes and standards, but it primarily focuses on enforcement and compliance rather than direct regulation of fire alarm installations. The Texas Department of Safety is more associated with law enforcement and public safety in general rather than specifically regulating fire alarm systems. The Texas Workforce Commission primarily deals with labor-related issues and does not have a mandate concerning fire safety or alarm systems. Thus, among the given options, the Texas Department of Insurance is the agency that specifically regulates the installation of fire alarms within Texas.