Explanation:

Recently, Turkmenistan gets observer status in World Trade Organization (WTO).  

• WTO is the only global international organization dealing with the rules of trade between nations.
• Any state or customs territory having full autonomy in the conduct of its trade policies may join the WTO.
• The WTO has 164 members and 23 observer countries. The US is the member of WTO.
• Only 16 countries are not WTO members. They are Aruba, Curacao, Eritrea, Kiribati, Kosovo, Marshall Islands, Micronesia, Monaco, Nauru, North Korea, Palau, the Palestinian Territories, San Marino, Sint Maarten, and Tuvalu. 

Hence only statements 1&2 are correct.