What is an index fossil?

a. a fossil formed by the impression of a once-living thing

b. a fossil that is found only in one particular time period

c. a fossil that appears to show an evolutionary change from one
species to the next

d. a fossil that appears periodically throughout earth's history

the answer is; comparing the frequency of collisions with and without the device

this makes the anti-collision system an independent variable and the collisions a dependent variable. if there are fewer collisions with an anti-collision system that without, then it can be stated that the system is a success. essentially, collisions under an anti-collision system are compared with the frequency of collisions by cars with the human drivers.

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%