Which of the following shows the correct chronological order of the events occurring during callus culture?

• A
  Callus $\rightarrow$ Cell division $\rightarrow$ Explant $\rightarrow$ Addition of cytokinin $\rightarrow$ Cells acquire meristematic property
• B
  Explant $\rightarrow$ Cell division $\rightarrow$ Addition of cytokinin $\rightarrow$ Cells acquire meristematic property
• C
  Explant $\rightarrow$ Cell division $\rightarrow$ Callus $\rightarrow$ Addition of cytokinin $\rightarrow$ Cells acquire meristematic property
• D
  Callus $\rightarrow$ Explant $\rightarrow$ Cell division $\rightarrow$ Addition of cytokinin $\rightarrow$ Cells acquire meristematic property