To determine which pass is not located in Arunachal Pradesh, we must first understand the geographical layout and significance of the passes mentioned in the options.

1. Kumjawng Pass: This pass is located in Arunachal Pradesh and serves as a route connecting various regions. It is known for its strategic geographical position.
2. Yonggyap Pass: This pass is also located in Arunachal Pradesh. It is used as a traditional route and holds significance in regional transit and cultural exchanges.
3. Bomdi La: Also known as Bomdila Pass, this is situated in Arunachal Pradesh. It is quite famous and acts as a gateway to the rest of the state from the plains of Assam.
4. Muling La: This pass is not located in Arunachal Pradesh. It is essential to recognize geographical borders and pass locations to answer questions regarding regional access and connectivity.

By analyzing the geographical locations and strategic importance of these passes, the correct answer to the question "Which one of the following is not a pass of Arunachal Pradesh?" is Muling La.

In competitive exams, such questions test your knowledge of Indian geography, specifically the strategic passes that connect various regions, and familiarizing yourself with these geographical details is beneficial.