Which of the following Transformer can have tap changer?

It seems like there might be a misunderstanding in your question. The term "Transformer" can refer to two different things: the Transformer model architecture used in natural language processing (NLP), and the electrical device used to transfer electrical energy between two or more circuits through electromagnetic induction.

If you are referring to the electrical device, a tap changer is a feature in a power transformer. It is not directly related to the Transformer model used in NLP. A tap changer is a mechanism that allows the adjustment of the turns ratio of the transformer to regulate the output voltage. Transformers with tap changers are typically used in power distribution systems to compensate for variations in the incoming voltage or load conditions.

If you are referring to the Transformer model in NLP, it doesn't have anything to do with tap changers or electrical systems. It's a deep learning model architecture developed for processing sequences of data, particularly well-known for its applications in natural language understanding and generation tasks.

If you have a specific context or more details about what you are asking, please provide them so I can offer a more accurate and relevant response.