1st option is correct. 

The Association of Southeast Asian Nations (ASEAN) was formed in 1967 by Indonesia, Malaysia, the Philippines, Singapore, and Thailand to promote political and economic cooperation and regional stability. Brunei joined in 1984, shortly after its independence from the United Kingdom, and Vietnam joined ASEAN as its seventh member in 1995. Laos and Burma were admitted into full membership in July 1997 as ASEAN celebrated its 30th anniversary. Cambodia became ASEAN’s tenth member in 1999.