The correct answer is compounding. Compounding is the word formation process in which two or more lexemes combine into a single new word. In this case, the words soap and opera were combined to form the compound soap opera. Some compounds have obvious meanings as they can be inferred by the meaning of the original words, for example, a blueberry is a berry that is blue. However, other compounds have meanings that are less obvious, such as soap opera, a TV program about the lives of a particular group of characters, called this way because the original sponsors of such programs were soap manufacturers.