For the following pseudocode functions, choose the big O notation that accurately describes its worst-case complexity.

In a language that supports OOP paradigm, we have the following code that serializes the content of a shopping cart to JSON format:

class ShoppingCart
  private content : Dictionary<int, string> 

  public function serialize() : string
    return new JsonSerializer().serialize(content.clone())
  end function
end class

class JsonSerializer  
  public function serialize(value : Dictionary<int, string>) : string
    ' Code that serializes dictionary to JSON format and returns it as string
  end function
end class

A client now wants to have the possibility for allowing plugins to serialize the shopping cart content to their own formats (e.g., XML). Select lines of code that, together, would extend the code above to allow this extensibility.

(Select all acceptable answers.)

Answer the questions below regarding correct usage of data structures.