Final answer:
The word 'and' is the correct choice to fill in the blank, indicating that security specialists from both private companies and government agencies will convene for a discussion.
Step-by-step explanation:
The correct word to complete the sentence "Security specialists from private companies and government agencies will meet to discuss the problem." is and. This conjunction is used here to connect two groups that will participate in the meeting: private company security specialists and government agency representatives.
The word and implies that both groups will be present and contribute to the discussion regarding security issues.
The use of 'and' indicates that both security specialists from private companies and government agencies will meet to discuss the problem.