Which of the following materials is known to absorb wireless signals?

Water is known to absorb wireless signals due to its molecular structure and the way it interacts with electromagnetic waves. When radio waves or microwaves pass through water, the energy from these signals is absorbed, leading to attenuation or weakening of the signals. This characteristic makes water a significant factor affecting wireless communication, especially in environments such as homes, where humidity and the presence of water (like in plumbing) can impact signal quality.

In contrast, materials like wood, glass, and plastic do not significantly absorb wireless signals and typically have minimal impact on signal propagation. While these materials can reflect or refract signals, they do not absorb them to the same extent as water. This distinction is crucial when designing and troubleshooting wireless networks, as it helps in understanding how different environments can affect signal strength and quality.