Ozone hole refers
a. hole in ozone layer
b. decrease in the ozone layer in troposphere
c. decrease in thickness of ozone layer in stratosphere
d. increase in the thickness of ozone layer in troposphere

The Correct Answer is A

Explanation:

ozone hole:

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.

"a.) well–developed vascular system."