Which of the following natural resources is most readily available to all organisms?

Step 1: Analyze the question The question asks which natural resource is most readily available to all organisms. The key phrases are "most readily available" and "all organisms," which means we need a resource found almost everywhere that nearly every living thing can access without much effort.

Step 2: Explain the concept Natural resources differ in how accessible they are:

• Oil is buried deep underground and is not used directly by living organisms.
• Water is vital to life, but it is not found everywhere. Deserts, dry seasons, and dry habitats limit its availability, and many organisms must search for it.
• Air surrounds every organism on Earth, on land and in water (as dissolved gases). It supplies oxygen for respiration and carbon dioxide for photosynthesis, and it is freely available with no effort needed.
• Food must be hunted, grown, or manufactured, and organisms often compete for it.

Step 3: Work through the options

• A. Oil: not accessible to most organisms. ❌
• B. Water: essential, but it can be scarce in some environments. ❌
• C. Air: present everywhere and freely available to all organisms. ✅
• D. Food: requires effort and competition to obtain. ❌

Step 4: Answer The correct option is C. Air.

Tip: When you see "most readily available" in an exam question, ask yourself: "What do organisms get without searching or competing?" Air is all around us, so it is usually the answer. Also remember that water, though essential, can be limited by location and season.