Removing oxygen, removing moisture and killing spoilage organisms are all ways to food.

Answer is preserve

1. Removing oxygen: The removal of oxygen from food preserves the food by avoiding the oxidation of food that leads to spoilage.Cover the food or vegetable tightly in air tight container to avoid oxygen reaching the cut cells which will cause  spoilage of food.The fruits and vegetables should immediately be boiled or cooked to prevent oxidation.

2. Removing moisture: The removal of excess water from vegetables and fruits helps in preservation of food. The bacterial growth that spoils the food grows in moist environment hence reducing the moisture content will preserve food.

3. Killing spoilage organism: The ultraviolet light and infrared light are used to kill the organisms causing spoilage of food. Flash technique is also used for preserving food from microorganism.

some of your causes might be acidic rain or natural wildfires that cause the parks to be degraded

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