The exact extract asks what Huawei rack-level/pack-level optimization design mainly solves. The correct answer is A. Reduce the impact of battery inconsistencies on the system. In large ESS deployments, battery packs and racks do not behave identically over time. Their SOC, SOH, temperature, internal resistance, and aging rates differ, and these inconsistencies reduce usable capacity and may force the whole system to follow the weakest pack or rack. Huawei's Smart String ESS design uses pack-level optimization, rack-level management, and refined electronic control to reduce the negative effect of these inconsistencies. The purpose is not primarily to slow every cell's chemical degradation, increase physical energy density, or expand the nominal rack capacity. Those may be indirect commercial benefits, but the technical design principle is mismatch mitigation and refined energy management. Huawei describes pack-level optimization, rack-level management, and safety design as controlling lithium-battery inconsistency and uncertainty, improving available capacity and safety. Reference: Huawei FusionSolar Smart String ESS and PV+ESS integration materials.