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The correct classification system that uses the symbols "CL" and "CH" is the Unified Soil Classification System (USCS). In this system, "CL" designates "Lean Clay," while "CH" indicates "Fat Clay." The USCS categorizes soils based on their grain size and plasticity characteristics, making it particularly useful for engineering applications where understanding soil behavior is critical for design and construction.

The USCS is designed to provide a clear and effective way to classify fine-grained and coarse-grained soils, which assists engineers in predicting how these soils will behave under various conditions. For example, CL and CH distinctions are essential when evaluating the load-bearing capacity and drainage characteristics of clay soils, which can greatly influence foundations and other infrastructure.

Other classification systems like the AASHTO Soil Classification System and the Soil Conservation Service Classification may categorize soils based on different properties or purposes, but they do not utilize the same symbols. The AASHTO system primarily focuses on soil suitability for highway construction, using different classifications and notation, while the Soil Conservation Service Classification emphasizes agricultural suitability. The Engineering Classification System, although aimed at providing engineering-related soil categories, also does not employ the same coding as the USCS.