Explanation: The consolidation of authority in post-colonial India was a multifaceted process that involved several key steps, with the ratification of the constitution being one of the most significant. The Indian Constitution, adopted on January 26, 1950, was a landmark document that provided a legal framework for the governance of the newly independent nation. It was drafted by a Constituent Assembly, which was elected by the provincial assemblies of British India.
The constitution was crucial for several reasons:
1. **Legal Framework**: It established a legal system that would govern the actions of the state and its citizens, ensuring that all actions were in accordance with the law.
2. **Democratic Governance**: It defined the structure of the government, including the roles of the executive, legislative, and judiciary branches, and established a system of checks and balances.
3. **Fundamental Rights**: It guaranteed fundamental rights to all citizens, such as the right to equality, freedom of speech, and the right to constitutional remedies.
4. **Integration of States**: It provided a mechanism for integrating the diverse regions of India into a single nation, addressing issues of language, culture, and regional autonomy.
5. **Economic and Social Justice**: It included provisions for economic and social justice, aiming to reduce inequalities and promote social welfare.
While other actions, such as establishing diplomatic relations with other countries or addressing linguistic and cultural issues, were also important, the ratification of the constitution was the cornerstone of consolidating authority. It provided a stable and unified legal foundation for the new nation, ensuring that the transition from colonial rule to self-governance was smooth and orderly.
In contrast, the other options do not accurately reflect the primary methods of consolidating authority. Expelling Sikhs from the region is not a historical fact and does not align with the inclusive approach of the Indian government. Making English the official language, while significant, was not the primary method of consolidating authority. Opening diplomatic relations with Russia, while important for international relations, was not a primary method of consolidating internal authority.
Therefore, the correct answer is (A) Ratifying the constitution, as it was the most significant step in establishing a legal and political framework for the new nation, ensuring stability and unity in the post-colonial era.