Step 1: Understand the methods listed
The Electric Resistivity method is used to determine the subsurface characteristics, such as water-bearing formations. This method involves measuring the electrical resistivity of the ground, which varies with the presence of water.
The Test Boring method is used to physically sample the subsurface, but it does not directly help in exploring groundwater unless combined with other techniques.
The Tracer method involves using chemical tracers to track the movement of water, often used in hydrological studies but not primarily for groundwater exploration.
The Remediation method refers to the treatment of contaminated groundwater and is not used for its exploration.
Step 2: Choose the correct method for groundwater exploration
The Electric Resistivity method is the most commonly used method for geophysical exploration of groundwater, as it helps to detect areas with groundwater and estimate their potential.