‘Project Loon’, sometimes seen in the news, is related to

Project Loon was Google's (now Alphabet's) effort to provide internet connectivity using a fleet of high-altitude balloons floating in the stratosphere, roughly 18 to 20 km above the earth. Each balloon acted as a relay node that beamed signals to ground users and other balloons. So the answer is B, wireless communication technology.

Why the other options are wrong:

• A (waste management): The project has nothing to do with garbage processing or recycling.
• C (solar power production): The balloons used solar panels to power their systems and stay aloft, but the purpose was connectivity, not power generation.
• D (water conservation): No link to water management of any kind.

The core concept is using stratospheric platforms to extend broadband to remote and under-served areas where laying fibre or building towers is costly. For Mains GS-3, this ties into digital infrastructure, the digital divide and how emerging technologies can support inclusive growth. Note that Google wound down Loon in January 2021 after it did not become commercially viable, so if a question asks about its current status, the answer has changed.

Trap: Candidates pick C because the balloons ran on solar energy. The power source was an enabling feature, not the purpose of the project.