ASEAN was established in 1967 by signing:

Bangkok Declaration

The correct answer is option (3) - Bangkok Declaration

ASEAN was established in 1967 by 5 countries of this region: Indonesia, Malaysia, Phillippines, Singapore, and Thailand, by signing The Bangkok Declaration.  The objectives of ASEAN were primarily to accelerate economic growth, and through that social progress and cultural development, the secondary objective was to promote regional peace and stability based on the rule of Law and principles of the United Nations Charter. Over the years, Brunei Darussalam, Vietnam, Lao PDR, Myanmar and Cambodia Joined ASEAN taking its strength to 10.