Atoms are not changed in a reaction. They are just

rearranged

Explanation:

Atoms are the most basic unit of matter that makes up elements. Atoms are made up of electrons orbiting a nucleus comprising protons and neutrons.

The atomic number, is defined as the number of protons in an atom, while the atomic mass, is the number of protons and neutrons.

In reaction, atoms are not created or destroyed, the atoms simply become rearranged in new formats; molecules are two or more atoms bonded together. Different molecules can join together to form compounds.

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.

thinking it would be d not too sure but i think it's right