Explanation:

About SCO

• The Shanghai Cooperation Organisation or the Shanghai Pact, which is an Eurasian political, economic and military organisation founded in 2001 in Shanghai with an aiming to maintain peace, security and stability in the region. 
• The Chairmanship of SCO is by rotation for a year by Member States.
• China, Kazakhstan, Kyrgyzstan, Russia and Tajikistan were the original 5 founding members of the organisation who found the Shanghai Five Group. 
• The group was then renamed to Shanghai Cooperation Organisation with Uzbekistan joining the organisation in 2001.
• There are eight member states in the SCO at present, namely, China, Kazakhstan, Kyrgyzstan, Russia, Tajikistan, Uzbekistan, Pakistan and India (both joined in 2017).

There are about four observer states and six dialogue partners in the SCO at present

• Observer States: Afghanistan, Belarus, Iran and
• Dialogue Partners: Armenia, Azerbaijan, Cambodia, Nepal, Sri Lanka and Turkey.

Objectives of the SCO

• To strengthen mutual trust among the neighbouring member states.
• To promote effective cooperation in various fields like economy, trade, politics, culture and research and technology.
• To ensure peace, prosperity, security and stability in the region, and
• To establish a democratic, fair and rational international eco-political order.

Organisational Structure of the SCO

• The supreme decision-making body in the Shanghai Cooperation Organisation is the Heads of State Council.
• The second highest body of the SCO is the Heads of Government Council.
• Whereas the SCO secretariat, Beijing and the Executive Committee of the Anti-Terrorist Structure, Tashkent are the permanent bodies of the SCO.
• Regional Anti-Terrorist Structure (RATS) – Established to combat terrorism, separatism and extremism.

Hence only statements 2&3 are correct.