The exact extract asks which feature can increase the energy yield of a PV system. The correct answer is C. Module-level optimization. Module-level optimization improves generation by reducing mismatch losses between PV modules. In a string system, shading, dirt, aging, module orientation differences, or manufacturing variation can cause one weak module to reduce the output of the entire string. Huawei optimizer technology allows modules to work more independently and helps each module operate closer to its maximum power point. That directly increases energy yield. AFCI is a safety function for arc-fault detection and shutdown; it protects against fire risk but does not primarily raise generation. Smart string-level disconnection is also a safety and fault-isolation feature. Module-level shutdown improves emergency safety, not energy output. Therefore, only module-level optimization directly matches the energy-yield improvement requirement. Reference: Huawei HCSA-Sales-Smart PV V2.0 C & I Solution and optimizer training extract.