$I. ... A...$ is the ability of a cell to take up foreign $DNA$.
$II.$ The cell is treated with a specific concentration of a divalent cation such as $... B...$ to increase the pore size in the cell wall.
$III.$ In $...C...$ method,recombinant $DNA$ is directly injected into the nucleus of an animal cell.
The most appropriate option regarding $A, B$ and $C$ is:

• A
  $A-$Competency,$B-$Calcium,$C-$gene gun method
• B
  $A-$Transformation,$B-$Sodium,$C-$microinjection method
• C
  $A-$Competency,$B-$Calcium,$C-$microinjection method
• D
  $A-$Transformation,$B-$Sodium,$C-$gene gun method