(d) Ensuring linguistic accommodation.
Brussels formed a separate government to give equal representation to both Dutch and French-speaking communities, ensuring linguistic accommodation.
Source: Accommodation in Belgium, Chapter 1
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The passage clearly states that Brussels needed a separate government where both communities have equal representation — this was to accommodate the linguistic conflict between Dutch and French speakers in the capital. Options (a), (b), and (c) are not mentioned in the context of forming Brussels' separate government.