Consider the program given below, in a block-structured pseudo-language with…

Consider the program given below, in a block-structured pseudo-language with lexical scoping and nesting of procedures permitted.

Program main;
  Var ...

  Procedure A1;
    Var ...
    Call A2;
  End A1

  Procedure A2;
    Var ...

    Procedure A21;
      Var ...
      Call A1;
    End A21

    Call A21;
  End A2

  Call A1;
End main.

Consider the calling chain: Main → A1 → A2 → A21 → A1

The correct set of activation records along with their access links is given by