Which of the following is not a member of ‘Gulf Cooperation Council’?

The correct answer is Iran. Iran is not a member of the Gulf Cooperation Council (GCC).

Let us understand this step by step.

Step 1: What is the Gulf Cooperation Council (GCC)?
The Gulf Cooperation Council, commonly known as the GCC, is a regional intergovernmental political and economic union established on May 25, 1981, in Abu Dhabi, UAE. It was formed to foster cooperation among Arab states of the Persian Gulf region in areas such as economics, security, politics, and social affairs.

Step 2: Who are the official members of the GCC?
The GCC has exactly six (6) member states, all of which are Arab monarchies located on or near the Arabian Peninsula:

1. Saudi Arabia
2. United Arab Emirates (UAE)
3. Kuwait
4. Qatar
5. Bahrain
6. Oman

Step 3: Verifying the options against the member list
Now let us check each option provided in the question against the official GCC member list:

• Saudi Arabia — ✅ IS a member of the GCC.
• Oman — ✅ IS a member of the GCC.
• Kuwait — ✅ IS a member of the GCC.
• Iran — ❌ Is NOT a member of the GCC.

Step 4: Why is Iran excluded?
Although Iran is geographically situated along the Persian Gulf, it is not an Arab nation — it is a Persian country with a distinct language (Farsi/Persian), culture, and political system (an Islamic Republic, not a monarchy). The GCC was specifically formed as a coalition of Arab Gulf monarchies. Furthermore, Iran has historically had political tensions and ideological differences with the GCC member states, making it incompatible with the council's founding principles and membership criteria.

Conclusion:
Since Iran is neither an Arab state nor a monarchy, and has geopolitical differences with the GCC bloc, it has never been a member of the Gulf Cooperation Council. Therefore, among all the given options, Iran is the one that is not a member of the GCC.