Q: Fact: food is a source of energy for animals
Question: What is a source of energy for animals?

A: grains

Q: Fact: ice wedging is when ice causes rocks to crack by expanding in openings
Question: Ice wedging can be explained by pointing to

A: roads in wintery areas need constant fixing after winter

Q: Fact: the smell of rotting meat attracts flies
Question: The reason that flies can always find food is that they can smell

A: organism decay

Q: Fact: water is often brackish in an estuary
Question: Some human activities may create brackish like

A:
swimming tubs