Because ecosystems don't change over one day, they change over a long period of time. Plus, something that happens may be because of more than just one change.
The question can be changed into a new form:
Which element has the most negative electron affinity, or attraction for electrons? halogens have the highest electron affinities, and thus are more attracted to the electrons in the Hydrogen atom than any element in their respective periods.
In this case all the following choices are in the same period, thus Cl or Chlorine is the answer as it is a halogen.
Answer: I believe it is critical mass
Explanation:
