In resource geography, which type of resources are defined as those whose quantity is already known and measured?

Introduction / Context:
Questions on classification of resources are very common in school level economics and geography. Examinations often test whether the learner can distinguish between actual resources, potential resources, natural resources, and other related terms. Here we focus on a specific definition: resources whose quantity is already known and measured. Understanding this classification helps students interpret economic and environmental statistics correctly.

Given Data / Assumptions:

• We are dealing with classification of resources as used in basic economics and geography.
• We have four main options: natural, actual, potential, and abiotic resources, plus an extra distractor.
• The key phrase is that the quantity of the resource is known.
• Standard textbook definitions are assumed.

Concept / Approach:
Resources are broadly grouped as actual and potential according to their stage of development and use. Actual resources are those which are surveyed, quantified, and currently being used. Potential resources are those which exist and may be useful in future, but their exact quantity and feasibility of use are not yet fully measured or exploited. Natural resources is a broader term and includes both actual and potential resources that come from nature. Abiotic resources are non living resources like minerals and metals. Therefore, the term that directly matches the idea of a resource with known quantity is actual resources.

Step-by-Step Solution:
1. Identify the key phrase in the question: resources whose quantity is known.2. Recall that actual resources have been surveyed and their quantity and quality have been determined by experts.3. Recognise that potential resources are believed to exist but are not fully surveyed or used, so their quantity is not fully known.4. Understand that natural resources is a broad category that does not specify whether quantity is known or unknown.5. Conclude that the best match to the given definition is actual resources.

Verification / Alternative check:
One way to verify is to think of examples. Coal deposits already mapped and mined in a particular region are actual resources because the reserves have been estimated and are being used. Wind energy in a region where no large scale wind farms have yet been built is a potential resource, because although the wind is available, its exploitable quantity has not been fully studied or tapped. This comparison confirms that the phrase in the question is associated with actual resources rather than potential or other types.

Why Other Options Are Wrong:
Option A: Natural resources simply refers to resources obtained from nature such as air, water, soil, and minerals. It does not guarantee that their quantity is known.
Option C: Potential resources are those that exist and may be used in the future but their quantity and feasibility of extraction are not fully studied, so they do not match the definition of known quantity.
Option D: Abiotic resources are non living resources like minerals, metals, and rocks. Again, some abiotic resources may be known, some may not; the term does not define known quantity.
Option E: Biotic resources are living resources such as forests, animals, and fish. The term says nothing about whether their quantity has been surveyed and measured.

Common Pitfalls:
Students often confuse the pair actual and potential because both refer to usefulness. A helpful memory aid is that actual resources have actually been measured and used, while potential resources have potential use in the future. Another pitfall is to assume that the word natural means fully understood, which is not correct. Always focus on the definition given in the question, especially phrases like known quantity or measured reserves.

Final Answer:
Resources whose quantity is already known and measured are called actual resources.