Identify the correct pathway of electron transport in the $Z$-scheme.

• A
  $H_2O \rightarrow PS-II \rightarrow ETS \rightarrow PS-I \rightarrow NADP^+$
• B
  $H_2O \rightarrow PS-I \rightarrow ETS \rightarrow PS-II \rightarrow NADP^+$
• C
  $PS-I \rightarrow ETS \rightarrow PS-I$
• D
  $PS-II \rightarrow ETS \rightarrow PS-II$