Explanation: In digital logic, "positive logic" means a high voltage level represents a logic "1" (true), and a low voltage level represents a logic "0" (false). For the logic input levels shown in Figure 3E12 (which typically would depict one input as HIGH and the other as LOW, providing a diverse set of conditions for testing gate functions), we analyze the behavior of common logic gates: 1. **Test Point A (LOW):** If A is the output of an **AND gate** with one HIGH and one LOW input, its output will be LOW. An AND gate requires *all* its inputs to be HIGH for its output to be HIGH. 2. **Test Point B (HIGH):** If B is the output of an **OR gate** with one HIGH and one LOW input, its output will be HIGH. An OR gate produces a HIGH output if *any* of its inputs are HIGH. 3. **Test Point C (HIGH):** If C is the output of a **NAND gate** with one HIGH and one LOW input, its output will be HIGH. A NAND gate is an inverted AND gate. Since the AND operation of a HIGH and a LOW input results in LOW, inverting that LOW output gives a HIGH output. Therefore, with one HIGH and one LOW input, point A (AND gate) is LOW, point B (OR gate) is HIGH, and point C (NAND gate) is HIGH.