Your answer would be D because it is the only answer choice that would attract people.
The correct answer is A) at least 500.
The rocks in which the fossils are found, are more often then not, indicators of the age of the fossil itself. So if the estimate of the fossil's age is 500 MYA then the rock is of at least the same age, most of the time older then the fossil.
Answer:
The correct answer is B. Air pressure
The difference between the fertility rate and the death rate corresponds with the birth rate. When you take the number of children that have been born (alive) in a given year, and then minus the number of the people that have died in the same year, you get the birthrate. It can be positive, when there's more born children than people that died, or negative, when there's more people that died than born children.
