Explanation: Carbon microphones convert sound into electrical signals by varying the resistance of packed carbon granules. A diaphragm, vibrated by sound waves, compresses and decompresses these granules. * **Jarring or tapping** (A and B) can cause the carbon granules to settle unevenly or compact too tightly, a condition known as "packing." This reduces the microphone's sensitivity, introduces noise, or can temporarily/permanently impair its operation. * **Violent sound intensities** (C) can similarly lead to granule packing due to excessive diaphragm movement, or even cause physical damage to the diaphragm itself. Overloading can also introduce significant distortion. Since all these actions interfere with the delicate balance of the carbon granules, leading to poor performance or damage, none of them should be done to a carbon microphone while in operation.