What do astronomers call a system that is composed of more than two stars

If the type of food available changes, then…

The presence of iron oxides in rocks, formed during a specific time period, can be used as evidence of oxygen in the atmosphere during that time period. question 18 options: true false

Aline graph has a vertical axis labeled "average plant mass (g)" and a horizontal axis labeled "concentration of ammonium nitrate (mg/l)." what information is conveyed by a point plotted with coordinates (10,40)? keep in mind coordinates are written as (x coordinate, y coordinate).