In the nuclear security passage, choose the correct preposition to complete the phrase: "civilian holdings __________________ nonnuclear weapon states".

Introduction / Context:
This question continues the nuclear security passage and focuses on the correct preposition used with geographical and political entities. The phrase "civilian holdings __________ nonnuclear weapon states" refers to assets that exist inside states which do not possess nuclear weapons. Getting prepositions right is a key part of writing clearly about international relations and geography.

Given Data / Assumptions:

• The phrase is: "civilian holdings __________________ nonnuclear weapon states".
• Options are: into, for, in, about, within.
• The context refers to nuclear materials present inside states that do not own nuclear weapons.
• We must select the preposition that naturally connects holdings and states.

Concept / Approach:
Prepositions such as "in" and "within" describe location inside an area or state. However, "in" is the most straightforward and common preposition used with countries and states. The expression "holdings in a country" is standard English. The correct choice should express that the civilian holdings are located inside nonnuclear weapon states.

Step-by-Step Solution:
Step 1: Understand that "civilian holdings" refers to stocks or quantities of nuclear materials under civilian control. Step 2: The phrase must state where these holdings are located, which is inside nonnuclear weapon states. Step 3: Try "in": "civilian holdings in nonnuclear weapon states" clearly and correctly indicates location. Step 4: Consider "into". This suggests movement from outside to inside and is wrong when we simply want to describe existing location. Step 5: "For" would indicate purpose or benefit, as in "laws for citizens", which is not intended here. Step 6: "About" normally means concerning or regarding, and does not express physical or jurisdictional location. Step 7: "Within" can also express location inside, but "holdings within nonnuclear weapon states" is slightly more formal and less common than the simpler "holdings in nonnuclear weapon states". Exams generally expect the most natural and direct choice. Step 8: Therefore, "in" is the best preposition to complete the phrase.

Verification / Alternative check:
Consider similar sentences: "investments in developing countries", "assets in foreign states", and "nuclear facilities in nonnuclear weapon states". All use "in" to show that something is located inside a particular country or group of countries. Substituting any other preposition would sound strange or change the meaning, confirming that "in" is correct.

Why Other Options Are Wrong:

• into: Implies movement or direction, as in "go into the room", not static location.
• for: Suggests purpose or benefit, not where holdings are physically or legally located.
• about: Means concerning or regarding, which does not fit here.
• within: Possible in some contexts, but "in" is the more straightforward, idiomatic choice and is what exam questions typically expect.

Common Pitfalls:
A common mistake is to overuse "within" because it sounds formal, even when "in" is more natural. Another pitfall is not distinguishing clearly between prepositions of location and those of direction or purpose. To avoid such errors, remember typical phrases from news and academic sources and note how they talk about assets, investments, and holdings in various countries.

Final Answer:
The correct preposition is in, giving the phrase "civilian holdings in nonnuclear weapon states".