Explanation:

There are a few ways to clean up oil spills including

• Skimming: It involves removing oil from the sea surface before it is able to reach the sensitive areas along the coastline.
• In situ burning: It means burning a particular patch of oil after it has concentrated in one area.
• Releasing chemical dispersants helps break down oil into smaller droplets. It makes it easier for microbes to consume, and further break it down into less harmful compounds.
• Natural actions in aquatic environments such as weathering, evaporation, biodegradation and oxidation can also help reduce the severity of an oil spill. It also accelerates the recovery of an affected area.
• Sorbents: Various sorbents (e.g., straw, volcanic ash, and shavings of polyester-derived plastic) that absorb the oil from the water are used.
• Dispersing agents: These are chemicals that contain surfactants or compounds that act to break liquid substances such as oil into small droplets. They accelerate its natural dispersion into the sea.
• Biological agents: Nutrients, enzymes, or microorganisms such as Alcanivorax bacteria or Methylocella silvestris that increase the rate at which natural biodegradation of oil occurs are added.

Hence option 4th is correct.