Geophysical Exploration Method for Minerals and Oils

The question asks about the method of exploration specifically developed for prospecting useful minerals and oils.

Let's look at the options provided:

• Geo physical: Geophysical methods involve studying the physical properties of the Earth's subsurface to detect geological features that may indicate the presence of minerals or hydrocarbons (oil and gas). Techniques include seismic surveys, gravity surveys, magnetic surveys, and electrical methods. These methods are widely used in the early stages of exploration to cover large areas relatively quickly and identify potential targets for further investigation.
• Rotary boring: This is a drilling technique used to bore holes into the ground. While drilling is essential in mineral and oil exploration, it is typically done after initial exploration methods like geophysical surveys have identified promising areas. Drilling is used to collect samples (cores) or test the presence and quality of the resource at a specific location. It's more of a direct investigation or extraction method than a broad exploration method.
• Sub surface sounding: This is a general term that can encompass various methods to investigate the subsurface, including some geophysical techniques or simpler methods like probing. However, "Geophysical" is a more specific and widely recognized category of methods developed precisely for large-scale prospecting of resources like minerals and oil.
• Percussion boring: Similar to rotary boring, this is another drilling method that uses a pounding action to advance a borehole. Like rotary boring, it's primarily used for sampling or testing after potential targets have been identified, not as a primary method for initial broad exploration or prospecting over large areas for minerals and oil deposits.

Based on the purpose described – prospecting useful minerals and oils – the geophysical method of exploration is the most appropriate answer. Geophysical surveys are a fundamental tool in modern mineral and petroleum exploration, designed specifically to locate hidden deposits by measuring physical properties.