OFFICIAL EXPLANATION

The correct answer is A. The word "despite" is a clue that this sentence establishes a contrast. The contrast is between how the belligerent man presents himself in public and the insecure person he really is. The word "hauteur" means "arrogance," which is the opposite of insecurity. Choice B, "timidity," essentially means "insecure," and someone who is belligerent is not timid, so this answer is incorrect. Choice C creates an issue of redundancy, since "aggression" is the same thing as "belligerence." Choice D, "mendacity," means "dishonesty," which may be a negative trait, but it is not the opposite of insecurity. Choice D, "magnanimousness," means "generosity," which does not make sense in this context.