'Project Loon', sometimes seen in the news, is related to

Answer

wireless communication technology

(a) Waste management technology: Incorrect. Project Loon was not about garbage processing or waste disposal systems.
(b) Wireless communication technology: Correct. Project Loon was a Google/Alphabet initiative using high-altitude balloons to provide internet/connectivity in remote areas, so it relates to wireless communication.
(c) Solar power production technology: Incorrect. Though balloons used solar-powered equipment, the project’s purpose was not solar energy generation.
(d) Water conservation technology: Incorrect. It had no link with water saving, irrigation, or conservation methods.