After implantation,finger-like projections on the trophoblast are called $...A....$ which are surrounded by $...B..$ and maternal blood. Here $A$ and $B$ refers to

• A
  $A-chorion; B-foetal\; cell$
• B
  $A-chorionic\; villi; B-uterine\; tissue$
• C
  $A-uterine\; tissue; B-chorionic\; villi$
• D
  $A-foetal\; cell; B-chorion$