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.
The increase in number of people
The main idea of this paragraph is A
Fulcrum I believe
hope it helps
her is this from google
"A system of temporary reference points established in the field allows users to move freely within the study area without losing the geo-referencing. It allows the user to perform the mapping of trees, deadwood, transects, repeated measurements and data verification."
