B. One
because an independent variable is something you change. So in a scientific experiment you only change one thing. If you happen to change more than one thing then the test becomes unfair therefore you should repeat and make sure that only one thing is changed this time.
Answer:
I like dogs but cats hate dogs
B. Subtract those from those in the area from those in or arriving at the area.
The promise of jobs and prosperity, among other factors, pulls people to cities. Half of the global population already lives in cities, and by 2050 two-thirds of the world's people are expected to live in urban areas. But in cities two of the most pressing problems facing the world today also come together: poverty and environmental degradation.
Answer:
bacteria, archaea, plants, protists, animals, and fungi,
Explanation:
