Explanation: A simple function generator is designed to produce fundamental, distinct waveforms used across various electronic and radio frequency applications. * **Sine Waves** are essential for testing linear circuits, frequency response, and filter characteristics, as they represent a pure, single frequency. * **Square Waves** are rich in odd harmonics, making them useful for testing digital circuits, switching characteristics, and as a source for frequency multiplication in synthesizers. Their fast rise and fall times test slew rate and transient response. * **Triangular Waves** are often generated by integrating a square wave, and conversely, a square wave can be derived from a triangular wave using a comparator. Triangular waves are valuable for linearity testing, voltage-controlled oscillators (VCOs), and ramp generation. They also serve as an intermediate step in generating shaped sine waves in many function generators. These three waveforms form the core set because they are distinct in their harmonic content and primary applications, and can often be easily derived from one another within the instrument itself. Options B and C are incomplete, missing key fundamental waveforms. Option A describes a modulation technique rather than a standard inherent waveform provided by a basic function generator.