Which one of the following countries is not a member of the Nuclear Suppliers Group (NSG), the cartel of nuclear fuel and technology suppliers?

Introduction / Context:
The Nuclear Suppliers Group, commonly called the NSG, is an important export control regime that seeks to prevent nuclear proliferation by regulating the export of materials, equipment, and technology that can be used for nuclear weapons. This question checks awareness of which states belong to this group and which do not. For aspirants of competitive examinations, knowledge of such strategic groupings is important because it is frequently linked with discussions on nuclear security, international diplomacy, and India relations with global powers.

Given Data / Assumptions:

• The question mentions the Nuclear Suppliers Group and lists four countries as possible answers.
• France, Russia, and the United States of America are all major nuclear powers.
• Iran is a country whose nuclear programme has often been under international scrutiny.
• The task is to identify which of these is not part of the NSG membership.

Concept / Approach:
The conceptual step is to understand that NSG membership mainly includes states that are recognised as suppliers of nuclear material and technology and that follow certain guidelines for nuclear export controls. Many leading industrialised nuclear capable states such as France, Russia, and the United States are NSG members. Iran, on the other hand, has been subject to sanctions and international negotiations regarding its nuclear programme and is not a recognised member of this suppliers group.

Step-by-Step Solution:
Step 1: Recall that the NSG originated in the 1970s after the Indian nuclear test and consists largely of developed nuclear supplier countries.Step 2: Confirm that France is a prominent nuclear exporter and has long been an NSG member.Step 3: Recall that Russia, as the successor of the Soviet Union, is also a major nuclear power and a member of the NSG.Step 4: Remember that the United States of America is a leading nuclear technology supplier and founding participant in the NSG.Step 5: Observe that Iran is usually discussed as a non compliant or monitored nuclear state, subject to negotiations, and is not part of the NSG. Therefore, Iran is the correct choice.

Verification / Alternative check:
A quick verification method is to cross check general news knowledge. India has sought NSG membership and has negotiated with the United States, Russia, and France for support, which indicates that these countries are already inside the group. Iran is rarely if ever mentioned as a nuclear supplier; instead it appears in reports about enrichment, inspections, or sanctions. This strong contrast in roles confirms that Iran is not an NSG member.

Why Other Options Are Wrong:
Option A, France, is wrong because France is a long standing NSG member and an exporter of civilian nuclear technology.Option B, Russia, is wrong because it is a major nuclear power and an active member of the Nuclear Suppliers Group.Option C, United States of America, is wrong because the United States is one of the key initiators and pillars of the NSG regime.

Common Pitfalls:
Students sometimes confuse nuclear supplier groups with broader forums like the United Nations or the Non Proliferation Treaty system and may assume that any controversial nuclear country, including North Korea or Iran, is linked formally to such clubs. Another pitfall is to think that only western powers are members, ignoring Russia participation. Careful reading of international news and a short list of NSG members can prevent such confusion in the exam hall.

Final Answer:
Iran