The correct answer is: B. two
The Social Justice Committee consists of at least two members, one of whom must be a woman and one of whom must be a member of a Scheduled Caste or Scheduled Tribe. This is to ensure that the committee is representative of the diversity of the community and that the voices of women and marginalized groups are heard.
Option A is incorrect because the committee must have at least two members, not one.
Option C is incorrect because the committee must have at least two members, not three.
Option D is incorrect because the committee must have at least two members, not four.