Explanation: Grounding the case of a high-voltage transformer is a fundamental safety practice in amateur radio and electrical engineering. **A) To protect personnel handling the equipment from shock:** This is a primary safety concern. If a high-voltage winding or component inside the transformer were to accidentally contact the metal case, the case would become energized with dangerous voltage. Grounding provides a low-resistance path for this fault current to flow directly to earth. This causes a fuse or circuit breaker to trip, opening the circuit and preventing the case from remaining live, thereby protecting anyone who might touch the equipment from severe electrical shock or electrocution. **B) To prevent high static voltages building up between the case and grounds:** High-voltage fields can induce charges on ungrounded metal objects through capacitive coupling. This can lead to a buildup of static electricity on the transformer case. While not as immediately dangerous as a direct fault, these static discharges can cause minor shocks, interfere with sensitive electronics, or even lead to arcing. Grounding dissipates these induced charges continuously, maintaining the case at zero potential relative to earth. Since both reasons are crucial for safe operation and protection, **C) A & B** is the correct answer.