In this theoretical passage on the nation, choose the correct word to complete the clause "When the nation is a national state, it is also a _____ for the protection of life".

Introduction / Context:
The passage now refers specifically to the nation when it appears as a national state. It says that in this form, the nation is also a blank for the protection of life. The missing noun must refer to an organised system or framework that can protect life. The question tests whether the learner can select a word that fits both the abstract academic style and the idea of a state as an organised arrangement.

Given Data / Assumptions:

• The sentence is When the nation is a national state, it is also a blank for the protection of life.
• The state is commonly viewed as an institutional arrangement.
• Options are structure, frame, harness, garter, organism.
• The required noun must be compatible with for the protection of life.

Concept / Approach:
In political theory, state institutions are often described as structures. The term structure emphasises the organised arrangement of institutions, laws, and norms. A structure for the protection of life therefore means an organised system whose purpose includes safeguarding human life. Our approach is to test each option and see which one best matches this theoretical language and the function described.

Step-by-Step Solution:
Step 1: Try frame for the protection of life. While frame can mean framework, it is usually used as framework for, not simply frame, and sounds less precise. Step 2: Try harness for the protection of life. Harness means equipment for animals or a controlling device and is unsuitable here. Step 3: Try garter for the protection of life. Garter is a piece of clothing, clearly irrelevant to political theory. Step 4: Try organism for the protection of life. Organism refers to a living being and does not fit naturally with the phrase for the protection of life. Step 5: Try structure for the protection of life. This is natural and accurate because a state can be seen as a protective structure. Step 6: Conclude that structure is the best and standard choice.

Verification / Alternative check:
We can verify by recalling how textbooks describe the role of states: The state is a structure for maintaining order and protecting citizens. The phrase legal and political structures is common. Thus, calling the national state a structure for the protection of life fits established terminology. None of the other options has this close connection with institutions and organised systems. Hence, structure is both semantically and stylistically correct.

Why Other Options Are Wrong:
Frame: Although loosely related to framework, the exact phrase frame for the protection of life is not standard, and structure is more precise. Harness: Implies restraint or control equipment, not a social system. Garter: A clothing item, completely out of context. Organism: A living entity, which would create confusion when the subject is an institutional state. Therefore, these options fail to capture the idea of a protective institutional arrangement.

Common Pitfalls:
A possible pitfall is overthinking and wanting a more unusual word when a straightforward academic term like structure is correct. Students should remember that many cloze questions favour standard textbook phrases. When a word closely matches both the idea and the style, it is usually the right choice, even if it seems simple compared with distractors.

Final Answer:
The correct answer is structure, giving the sentence When the nation is a national state, it is also a structure for the protection of life.