The correct answer is option 'C': Pacific Ocean.

The Clarion Clipperton Zone (CCZ) is indeed located in the Pacific Ocean. It is a vast area in the eastern Pacific Ocean, stretching from Hawaii to Mexico, covering an estimated 6 million square kilometers. This region is of great interest for deep-sea mining due to its abundance of mineral resources.

Below are the key details explaining why the correct answer is the Pacific Ocean:

1. Location:
The CCZ is located in the Pacific Ocean, specifically in the eastern part. It extends from approximately 4°N to 20°N latitude and from 115°W to 155°W longitude.

2. Geological Importance:
The CCZ is considered the most studied area of commercial interest for deep-sea mining. It is rich in polymetallic nodules, which are small metallic rocks scattered on the seabed. These nodules are composed of valuable minerals such as manganese, nickel, copper, and cobalt. The abundance of these resources has attracted significant attention from mining companies and researchers.

3. Exploration and Research:
The CCZ has been extensively explored and researched by various countries and organizations. Numerous scientific expeditions and surveys have been conducted to assess the potential environmental impact of deep-sea mining in this region. The International Seabed Authority (ISA), an intergovernmental organization responsible for regulating seabed mining, has granted exploration licenses to several countries and companies for conducting studies in the CCZ.

4. Environmental Concerns:
Despite the commercial interest in deep-sea mining in the CCZ, there are significant environmental concerns associated with this activity. The fragile deep-sea ecosystem, which supports unique and diverse marine life, could be severely impacted by mining operations. The potential disruption of benthic habitats, release of sediments, and disturbance to ocean currents are some of the major concerns. Therefore, it is crucial to carefully assess the environmental risks and establish proper regulations before any mining activities commence in the CCZ.

In conclusion, the Clarion Clipperton Zone (CCZ), the most studied area of commercial interest for deep-sea mining, is located in the Pacific Ocean. Its rich deposits of polymetallic nodules make it an attractive prospect for mining companies, but the environmental impacts need to be carefully considered and regulated.