The world population is estimated to be 7 billion people.
Answer:
the loss of potential gain from other alternatives when one alternative is chosen.
Explanation:
By studying it we can tell how long life has existed in earth and how different plants and animals are related to each other.
Answer:
D) No continent is smaller than Australia
Explanation:
You forgot to include B and D, but I've done this before. Having Australia be the smallest continent means no other contitnet can be smaller than Australia.