Wouldn't it be genetics? Or traits?
It shows that flow of energy in the ecosystem is "Uni-directional" means energy flows only in one direction never reverse
Hope this helps!
One-third of all waste in landfills are waste products. They are of no use. The rest of them is methane and other waste. Time to time methane is removed, for using it for different purposes. In landfills, the waste is buried and fresh waste is added to it every day. By anaerobic process, the waste is broken down into methane and other products.
C. because you may only have one manipulated variable to be able to know the responding variable.
Hydrogen and oxygen which makes up h2o / water