18 points i'll do brainliest which is the best reason for not using a moving car as a reference point?
select one:
a. the car will get out of sight too quickly.
b. it is difficult to tell other people which car you are using.
c. the car has moving parts, like rolling tires, that can be distracting.
d. it is difficult to determine which direction motion is occurring.

Americium-241 undergoes fission to produce three neutrons per fission event. if a neutron-absorbing material is mixed in with this sample so that the rate of neutron production drops down to 1.8 neutrons per fission event, which will be effective at achieving a critical mass? check all that apply. remove a deflective shield surrounding the sample. remove absorbent material mixed in with the sample. compress the sample of americium-241.