Which wireless connection occurs when there are no physical obstacles between the receiver and transmitter?

The correct answer isline-of-sight. In RF terminology, line-of-sight describes a wireless path where the transmitting antenna and receiving antenna have an unobstructed visual or RF path between them. Cisco’s RF power documentation defines this directly: antennas that can see each other without obstacles between them are considered to be in line of sight. This is especially important in outdoor, bridge, mesh, and point-to-point wireless designs, where buildings, terrain, foliage, or other obstructions can degrade or block the RF path.

The other options describe different RF behaviors.Attenuationis signal loss as RF energy travels through free space, cables, walls, or other materials.Reflectionoccurs when RF energy bounces off a surface such as metal, glass, or concrete, often contributing to multipath.Beamformingis an antenna/transmission technique that focuses RF energy toward a client or receiver to improve signal quality; it is not the condition of having no obstacles. Cisco mesh planning guidance also emphasizes verifying whether a wireless link has clear line of sight before deployment, reinforcing that LOS is a path condition, not a modulation or security feature. Reference topic:RF Fundamentals — RF propagation, path loss, line-of-sight, obstruction effects, and wireless link planning.