Introduction:
Biodiversity refers to the variety of life on Earth, including all species of plants, animals, and microorganisms, as well as the ecosystems they form. It plays a crucial role in maintaining the stability and functioning of ecosystems, providing various ecosystem services such as food production, water purification, and climate regulation. However, human activities have posed significant threats to biodiversity, leading to its decline at an alarming rate.

Explanation:
Among the given options, option 'B' - Bioremediation is not a threat to biodiversity. Here's why:

Habitat destruction:
Habitat destruction refers to the alteration or destruction of natural habitats, primarily caused by human activities such as deforestation, urbanization, and conversion of land for agriculture. This threat directly impacts biodiversity by reducing the availability of suitable habitats for various species, leading to population declines and even extinction. It disrupts the intricate web of interactions within ecosystems and can have cascading effects on other species dependent on the affected habitats.

Introduced species:
Introduced species, also known as invasive species, are non-native species that are introduced into a new area, either intentionally or unintentionally, by human activities. These species often outcompete native species for resources, disrupt ecological processes, and can drive native species to extinction. They can also alter the structure and functioning of ecosystems, reducing overall biodiversity and threatening the integrity of native ecosystems.

Over-exploitation:
Over-exploitation refers to the unsustainable use or extraction of natural resources beyond their capacity to regenerate. This threat includes overfishing, illegal wildlife trade, poaching, and unsustainable logging. Over-exploitation can lead to the depletion of populations, loss of genetic diversity, and disruption of ecological dynamics. It can result in the collapse of ecosystems and the extinction of species, thus posing a significant threat to biodiversity.

Bioremediation:
Unlike the other options, bioremediation is not a threat to biodiversity. Bioremediation is a process that uses living organisms, such as bacteria or plants, to clean up or detoxify contaminated environments. It is often employed to restore ecosystems impacted by pollution or industrial activities. Bioremediation can even contribute to the restoration of biodiversity by improving the quality of habitats and creating more favorable conditions for the re-establishment of native species.

Conclusion:
In summary, while habitat destruction, introduced species, and over-exploitation are all significant threats to biodiversity, bioremediation is not. Bioremediation is a valuable tool in environmental restoration efforts and can contribute to the recovery and conservation of biodiversity. It is important to address the threats posed by habitat destruction, introduced species, and over-exploitation to ensure the long-term survival of Earth's rich and diverse ecosystems.