Which test stands for a method of soil sampling using an instrumented probe?

The Cone Penetration Test (CPT) is specifically designed for soil sampling using an instrumented probe. During this test, a cone-shaped tip is pushed into the ground at a consistent rate while measuring the resistance of the soil. This provides valuable data about the soil's stratigraphy, strength, and other characteristics. The use of an instrumented probe allows for continuous data collection, which enables engineers to obtain high-resolution profiles of soil behavior at various depths.

In contrast, other tests listed do not utilize an instrumented probe for sampling. The Standard Penetration Test involves dropping a hammer onto a split-barrel sampler, which provides information about soil density and stratification but does not use an instrumented probe. The Modified Proctor Test and Standard Proctor Test are laboratory tests focused on determining the optimum moisture content and maximum dry density of soils through compaction, not in-situ sampling techniques. Therefore, the Cone Penetration Test is the only method mentioned that directly corresponds to soil sampling using an instrumented probe.