What is the biosphere?

• A. The atmosphere of Earth.
• B. All living things on Earth, including plants, animals, and humans.
• C. The oceans only.
• D. The crust of Earth.

Answer: (B)

Biosphere is about the living part of Earth—the global network of life and the environments that sustain it. It includes all living things—plants, animals, and humans—and the places they inhabit, plus the interactions among organisms and their surroundings like air, water, and soil. That focus on life and its connected habitats is why the best answer centers on all living things on Earth. The other options point to specific Earth layers (the atmosphere, the oceans, or the crust) but don’t capture the living networks that define the biosphere.