How do you calculate population density

Why is the huronian supergroup rock formation particularly interesting to scientists? because it looks like a cross-section of a giant, stone encyclopedia because it formed during the period when oxygen began to accumulate in the atmosphere because it contains unusually large amounts of oxygen and sulfur because it dramatically altered the planet's development when it first formed

Soil color only reflects the amount of organic matter present in soil.

Why do so many children develop illnesses in southern africa? a. poor nutrition due to poverty c. very bad air pollution b. climate many diseases thrive d. declining life expectancy