The correct answer to the question is option 3 - Bio remediation. This waste management technique involves the use of micro-organisms to remove or neutralize pollutants from contaminated sites. Micro-organisms such as bacteria, fungi, and algae are capable of breaking down or transforming various types of pollutants, including organic compounds and heavy metals. They can either degrade the pollutants into less harmful substances or store them within their cells.

Option 1 - Biosensor is not the correct answer because biosensors are devices that use biological components to detect and measure specific substances.

Option 2 - Bio magnification is a process where the concentration of certain substances increases in organisms higher up the food chain.

Option 4 - Bio concentration is a similar process where the concentration of substances increases in an organism through exposure to its environment, but it does not involve the use of micro-organisms for waste management.

Therefore, the correct answer is option 3 - Bio remediation.