Step 1: Understanding Pickling.
Pickling in Python refers to the serialization of a Python object (such as a list, dictionary, or class instance) into a byte stream. This byte stream can then be saved to a file or transmitted.
Step 2: Opposite process.
The inverse operation is known as Unpickling or de-serialization, which reconstructs the original Python object from a byte stream.
Step 3: Eliminate wrong options.
- Option 1: \texttt{read()} → This function reads data from a file; it is not a serialization process.
- Option 2: \texttt{write()} → This function writes data but does not perform serialization.
- Option 4: De-serialization → This is the reverse of pickling, i.e., unpickling.
Therefore, the correct answer is Pickling.
Final Answer: \[\boxed{\text{Pickling}}\]