Which of the following subatomic particles is negatively charged?

The subatomic particle that is negatively charged is the electron. In atomic structure, electrons are found in the electron cloud surrounding the nucleus and possess a negative electric charge. This negative charge is crucial as it allows electrons to interact with positively charged protons in the nucleus, thus forming stable atoms. The balance of negative charges from electrons and positive charges from protons leads to the overall neutrality of most atoms.

Protons, found in the nucleus, carry a positive charge, while neutrons are neutral and do not have any electric charge. The nucleus itself, composed of protons and neutrons, carries a positive charge because of the presence of protons. Therefore, in the context of the question and the subatomic particles listed, the electron is the only one that exhibits a negative charge.