Hint words: "commonalities" & "collaborative" ---> cooperation

Explanation
The second half of the sentence states that the prime minister has kept his
promise to cultivate a certain leadership style; the “by” that begins the first
part of the sentence indicates that the actions it describes are cited as
examples of this style of leadership. The blank, then, must be filled with a
word that describes the prime minister’s focus on recognizing commonalities
and promoting collaboration. “Cooperation” does this. None of the other
choices touches upon the prime minister’s efforts to work with others in the
political process; indeed, “ideology” and “differentiation” might well imply
the opposite.
Thus the correct answer is cooperation (Choice D)

By recognizing commonalities among all the major political parties and by promoting a collaborative decision-making process, the prime minister has made good on his promise to cultivate a leadership style that emphasizes _______.

Since he recognizes commonalities in all major political parties and promotes collaborative decision-making process, his leadership style would emphasize consensus and cooperation.

The correct answer choice is cooperation.
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