Final answer:
Complex tones consist of a combination of frequencies, including a fundamental frequency and several overtones (harmonics), which give musical instruments and voices their distinctive sounds.
Step-by-step explanation:
Complex tones are C) a combination of frequencies. When we hear a musical note, like middle C on a piano or a clarinet, we are hearing a mixture of the fundamental frequency and various overtones, also called harmonics. For instance, middle C on a trumpet will sound different from middle C on a clarinet because each instrument emphasizes a different set of overtones, despite having the same fundamental frequency.
These overtones are multiples of the fundamental frequency. The first overtone is the second harmonic, the second overtone is the third harmonic, and so on. This combination of the fundamental and overtones gives each instrument or voice its unique timbre or quality. In human speech, this principle applies as well; we shape our vocal tract to form different combinations of overtones that create recognizable sounds or speech.