ANS:E - All the above.

The statement "All the above" refers to the collective truth of all the options provided. Let's go through each option to understand why "All the above" is considered the true statement:

1. Plain ceiling provides the best property of diffusing light:
   • This statement suggests that a plain ceiling is effective at diffusing light. While it's true that certain ceiling materials and finishes can diffuse light effectively, it's essential to note that "best" is subjective and can depend on various factors such as the type of lighting used, the purpose of the space, and individual preferences. Therefore, while not universally true, in specific cases, a plain ceiling can indeed provide good light diffusion properties.
2. In the absence of beams, it is easier to install piping:
   • Beams in a building's structure can sometimes obstruct the installation of piping, ductwork, or other utilities. Therefore, the absence of beams can provide more open space, making it easier to install piping and other utilities. This statement is generally true, as it reflects a common advantage of beamless structural systems like flat slabs or beamless floor systems.
3. In the absence of beams, it is easier to paint:
   • Similar to the installation of piping, the absence of beams can make painting walls and ceilings easier. Beams can create obstructions and shadows that complicate the painting process. Therefore, in the absence of beams, painters have more open space and fewer obstacles to work around, making the painting process potentially easier and more efficient. Again, this statement is generally true, especially in large, open spaces where beams are typically located.
4. A flat slab is capable of withstanding concentrated loads:
   • Flat slabs are a type of reinforced concrete slab without beams between columns. They are designed to transfer loads directly to the columns without the need for beams. Flat slabs are known for their ability to distribute and withstand concentrated loads effectively due to their simplicity and direct load transfer mechanism. Therefore, this statement is true, as flat slabs are indeed capable of withstanding concentrated loads.