Uracil is found in RNA and not DNA. DNA instead has thymine
3, definitely. The other answers are all harmful to the environment or flat-out wrong. At least it gets the economy going and lets more people make a living... even if it's hurting the ozone.
Answer:
a.they work together to allow gas exchange
Explanation:
the trachea helps transport air to the lungs, the lungs fill with air, finally the alveoli convert the oxygen to the bloodstream
