III . Complete the sentences with the appropriate words. At present the nature of __ is explained by the electron theory. a) electrification b) history c) town

The correct answer is a) electrification.<br /><br />The sentence should read: "At present the nature of electrification is explained by the electron theory."<br /><br />Explanation: The electron theory explains the nature of electrification, which is the process of generating and controlling electric charge. The other options, "history" and "town," do not fit the context of the sentence.