We breathe our carbon dioxide, so do plants. Animals and plants get rid of carbon dioxide gas through a process called respiration.
North Vietnam (aka communist Vietnam) gaining control of the government, and caused American troops to leave Vietnam
Prediction 1 is best. Two hummingbirds with short or medium beaks had a baby with a mutation in its genes for the long-beak trait. Because long-beak hummingbirds are more likely to survive, that baby survived long enough to pass on its mutation, so the long-beak trait became more common over generations.
