Concept: The water portion of the Earth’s surface is referred to by a specific sphere name.
Explanation:The hydrosphere is the combined mass of water found on, under, and above the Earth’s surface.
It includes oceans, seas, lakes, rivers, groundwater, and atmospheric moisture.
This covers about 71% of the Earth’s crust with saltwater and freshwater bodies.
The other options are not correct: sial is the silicon–aluminium layer of the Earth’s crust, and the stratosphere is a layer of the atmosphere.
Answer: Hydrosphere (Option A).