Answer: Soil ph is a measure of acidity or basicity of a soil, measured in a slurry of soil mixed with water.
Explanation:
What are the factors? If you meant to attach something it's not there.
Answer:
The scientists believe that they arose in Africa and spread to the rest of the world.
Explanation:
A is not correct because the Homo sapiens is not the earliest ancestor of moern humans, but it is the latest.
B is not correct because such evidence is lacking, and even though the Homo sapiens mixed with other hominids in Eurasia and sub-Saharan Africa, they were not of the same species.
C is correct because the evidence suggests for now that the Homo sapiens arose in Africa, and through several migration waves spread out on the other continents.
D is not correct because the Homo sapiens has not been replaced by any other species, as they are the species nowadays known as humans.
I think the United States is a well developed country. Like if you see India or Africa they are still developing.
I hope this helps :)