The underlined phrase means 'a feeling of pride and mutual loyalty shared by the members of a group'.
Option A is incorrect. Bravery means 'courage'. The given phrase does not mean courage. Thus, it is not the correct answer.
Option B is correct. 'Loyalty' is an accurate word to describe the given phrase. Thus, it is correct.
Option C is incorrect. Subordination means 'The state of being subordinate to something'. Thus, it does not have the required meaning.
Option D is correct. The given phrase means 'a sense of mutual loyalty'. 'Mutual loyalty' means 'unity'. Thus, 'unity' is also correct.