Final answer:
The best completion for the diagram is 'B. Reversal of liberal trends in Supreme Court rulings,' reflecting the conservative influence of the appointment of Justice Antonin Scalia and the presidency of Ronald Reagan, which align with a narrow interpretation of the Constitution. Option number b is correct.
Step-by-step explanation:
The narrow interpretation of the Constitution generally refers to a conservative or strict constructionist approach to constitutional interpretation. It often leads to a minimization in the expansion of government powers, including limitations on the federal government's role in social programs and federal efforts to shape the economic landscape of the country.
Given this context, the best completion of the diagram that matches a narrow interpretation of the Constitution in the light of the appointment of Antonin Scalia and the election of Ronald Reagan, is B. Reversal of liberal trends in Supreme Court rulings. This answer reflects the conservative shift in the court's ideological balance that can be associated with the appointment of a conservative Justice like Scalia and the election of a conservative President like Reagan, both of whom were likely to favor a narrow interpretation of the Constitution.