Answer:
oxygen
Explanation:
oxygen is an essential nutrient which the body needs especially during respiration.
it help the blood cells do provide energy.
without oxygen, there is no gaseous exchange
In oxidation, oxygen is needed to create a chemical reaction.
You could argue with the fact that a common worker was allowed their own burial tomb. Back in ancient Egypt few were rich enough to have a Tomb built. Also the tomb seams to be a graveyard, which implies that this is a place specifically designated for the dead, which were usually not tombs but in places closer to town.
Symbiosis can vary between mutualism, parasitism, and commensalism, tho these grade into each other, it is often difficult to tell which is involved in a given relationship.
Estuary, is a partially enclosed body of water formed where a river flows in an ocean.
