Two children in a family are half sisters; that is, their mom remarried so they both have the same ...

Two children in a family are half sisters; that is, their mom remarried so they both have the same mom but different fathers. The oldest child has severe allergies to dust, eggs, pollen, and chocolate, but the mom,
 
  the second child's dad and the second child have no allergies at all. The oldest child may have inherited from her dad
 
  a.
  an MHC haplotype that favors a TH1 response
  b.
  an MHC haplotype that favors a TH2 response
  c.
  a genetic variation that causes increased production of cytokines that favor IgE production
  d.
  A and/or C
  e.
  B and/or C