The correct answer is Option 4 Explanation & Key Takeaways: • Air, water, climate, soil, natural vegetation, Human functions and landforms are all environmental factors. • The environmental factors affect everyday living, and play a key role in bringing health differences across the geographic areas. • Critical chemical attributes include levels of oxygen, nutrients, pH, salinity, and other chemicals in the environment. • Chemical environments are exposures in which strong concentrations of highly corrosive gases, fumes, or chemicals touch the surface. • The native vegetation depends on climate, topography, and biological factors plus many soil factors such as soil density, depth, chemistry, temperature, and moisture. • Water is an essential ingredient of animal and plant life crediting to its unique physical, chemical and biological properties. • Leaves from plants fall to the surface and decompose on the soil. • The chemical environment of the body that is in contact with implanted biomaterials can have a profound and deleterious effect on their performance as surgical devices. • Biological factors - Plants, animals, micro-organisms, and humans affect soil formation. • Hence the correct answer is option ४.