Choose the word or phrase among A, B, C or D that best fits the blank space in the following passage

What is the Association of Southeast Asian Nations (ASEAN) and what is its purpose? The Association of Southeast Asian Nations (ASEAN) is a multilateral organization which was ___(1)___ to give Southeast Asian states a forum to communicate ___(2)___ each other. Since the region had a long colonial past and a history of endemic warfare, there has never been much peaceful and constructive ___(3)___ between kings, presidents and other officials. A neutral forum was, ___(4)___, a very useful development for all of those countries.
ASEAN was formed as a result of the Bangkok ___(5)___ of 1967 and initially had five members: Thailand, Malaysia, Indonesia, ___(6)___ Philippines and Singapore. Brunei ___(7)___ joined in 1984 after it had won independence from Britain. Vietnam became the seventh member of the group, officially joining in 1995. ___(8)___ several years of negotiation, Myanmar and Laos joined in 1997 and the final member of the ten, Cambodia, joined in 1999. The only ___(9)___ state in Southeast Asia which is not a member of ASEAN is now East Timor. It is still ___(10)___ vulnerable and fragile to be able to participate for the foreseeable future.