Match the following with respect to stages of embryonic development in human.

Column $I$	Column $II$
$a$. Fully formed morula	$i$. By end of $7^{\text{th}}$ day after fertilization
$b$. Fully formed blastocyst	$ii$. $15$ days after fertilization
$c$. Completion of implantation process	$iii$. By end of $4^{\text{th}}$ day after fertilization
$d$. Fully formed gastrula	$iv$. By end of $10^{\text{th}}$ day after fertilization

Choose the correct option-

• A
  $A-III, B-I, C-IV, D-II$
• B
  $A-I, B-III, C-IV, D-II$
• C
  $A-III, B-II, C-I, D-IV$
• D
  $A-II, B-I, C-III, D-IV$