Answer:
down syndrome
Explanation:
people with down syndrome have an extra chromosome in the twenty-first pair
Answer:
Many small organisms can be preserved within these layers of sediment through time. The changing abundances of these fossils through time can tell us whether a change in the environment or climate was gradual or abrupt. Studying fossil pollen and other fossils helps scientists to learn more about climate change.
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.
