"If rainforests and tropical forests are the lungs of the Earth, then surely wetlands function as its kidneys." Which one of the following functions of wetlands best reflects the above statement?

The correct answer is Option 4.

Key Points

• Wetland is defined as areas of marshes, fen, peatland, or water whether natural or artificial, permanent or temporary with water. that is static or flowing, fresh, brackish, or salt including areas of marine water, the depth of which does not exceed six meters.
• These areas have the soil covered by water or are present either at or near the surface of the soil all year or for varying periods of time during the year, including during the growing season.
• Wetlands, natural and manmade, freshwater or brackish, provide numerous ecological services.
• The wetlands essentially act as the ‘kidneys of the landscape’, filtering and capturing sediment, and helping settle it to the bed of the wetland and the plants use these nutrients to grow which supports the whole ecosystem. 
• Importance of Wetlands:
  • Aquatic plants absorb heavy metals and excess nutrients. Hence Option 4 is correct.
  • They filter, clean, and store water and thus act as kidneys for other ecosystems.
  • It helps to regulate the amount of water as excess water from rainfall and floods gets absorbed and can be used in times of need.
  • It is the source of livelihood through fishing and rice farming to travel, tourism, and water provision.
  • Wetlands host a large variety of life, protect our coastlines, provide natural sponges against river flooding and store carbon dioxide to regulate climate change.
  • They provide habitat for wildlife and migratory birds and help in the conservation of the environment.