The Peninsula Shield Force is a military arm of the Gulf Cooperation Council (GCC). The GCC is a political and economic alliance consisting of six Arab countries in the Gulf region – Saudi Arabia, Kuwait, Bahrain, Qatar, the United Arab Emirates, and Oman. The purpose of the GCC is to enhance cooperation and integration among its member states.

Option 1, the Organization of Islamic Cooperation (OIC), is an international organization that focuses on promoting Islamic solidarity and cooperation among its member countries. The Peninsula Shield Force is not affiliated with the OIC.

Option 2, the Organization of the Petroleum Exporting Countries (OPEC), is a group of countries that coordinate and unify their petroleum policies. While some GCC member states are also members of OPEC, the Peninsula Shield Force is not related to OPEC.

Option 4, the Arab League, is a regional organization made up of Arab countries. While some GCC member states are also members of the Arab League, the Peninsula Shield Force is specifically associated with the GCC and not the Arab League.

Therefore, the correct answer is option 3, the Gulf Cooperation Council.