This statement is false!
Around 90% of all the ozone contained in the atmosphere is accumulated in the stratosphere - this area is also called the ozone layer due to the high concentration of ozone.
Troposphere is below the stratosphere, and it's the one that's closest to the earth.
Answer:
a) Yes! the American chestnut tree is a native species. The American chestnut tree was present before the Europeans arrived in North America in the 1600s. Since a native species has been defined as any species that was present in North America before the arrival of the Europeans, then it is a fact that the North American chestnut tree is a native species.
b) The chestnut blight is an invasive species that is native to east East Asia, and was accidentally introduced into North America around the early 1900s, when the Japanese chestnut was commercially cultivated in the United States.
c) Invasive species tend to proliferate at a very high rate because they lack some natural constraints in the new environment such as natural predators, competition, and as in the case of this chestnut blight; the host has no natural defense mechanism against them. These conditions allow them thrive more than they would in their natural environment, unchecked
d) Yes, I agree with this idea, albeit to some extent. The development of hybrid chestnut resistant to the chestnut blight will possibly return the forests back to how it was before the Europeans arrived in the 1600s, but the genetic conservation will be altered, since these new trees will be an hybrid of the old trees, and the forest won't truly be as it was before the 1600s
Follow the Pythagorean theorem which is

So fill in what we know which is a and b to get

then solve the squares to get
36+64=

add the two numbers to get
100=

then square root each side to get
10=c
Hope I could help, and I am really good at the <span>Pythagorean theorem so if you need more help just let me know.</span>