Explanation

Option D is correct: In sociology and developmental economics, Social Capital refers to the networks of social relationships, civic associations, shared norms, and the level of mutual trust, cooperation, and harmony existing within a society:

– Unlike Physical Capital (buildings, infrastructure, machinery — Option B), Human Capital (literacy, technical education, skills — Option A), or Demographic Dividend (working-age cohort — Option C), Social Capital measures the intangible institutional trust and cohesion that reduces transaction costs and facilitates collective community action.

Therefore, social capital corresponds to The level of mutual trust and harmony in the society — Option D.