What type of load refers to the effects of gravity and external environmental forces on a structure?

The correct answer is that environmental load refers to the effects of gravity and other external forces acting on a structure. This concept encompasses a broad range of factors, including snow loads, wind loads, and seismic loads, which all create stress on a building's structure due to environmental influences. Understanding the implications of environmental loads is critical in building design, as these loads can significantly impact the safety and integrity of a structure over its lifespan.

The other types of loads mentioned, such as dead loads, which are static loads from the structure itself (like walls and roofs), and live loads, which include temporary loads from occupants and furniture, do not fully account for the external environmental forces. Additionally, dynamic load refers to loads that can change over time, like moving vehicles on a bridge, but does not specifically address the influence of environmental factors. Thus, environmental load is the most comprehensive category for the effects of gravity and external forces in building construction.