What power does the commission have to compel attendance of witnesses and the production of evidence?

The commission's power to compel the attendance of witnesses and the production of evidence is best identified as subpoenas. A subpoena is a legal document that requires an individual to appear at a specific time and place to testify or to produce certain documents or evidence. This instrument is essential in ensuring that the commission can gather necessary information to perform its duties effectively, particularly during investigations or hearings.

While notifications serve to inform parties about proceedings, they do not have the same compulsion aspect as subpoenas. Summons are typically used to notify a person that a legal proceeding is being initiated against them, but they do not directly compel testimony or document production in the same manner. Search warrants are used by law enforcement to enter a property to search for evidence of a crime; they are not relevant in the context of a commission's investigative powers over witnesses. Thus, subpoenas stand out as the correct answer due to their specific legal purpose in compelling testimony and evidence.