Answer:
A
Explanation:
1 half-life = .4 kg = 15 years
2 half-life = .2 kg = 30 years
3 half-life = .1 kg = 45 years
4 half-life = .05 kg = 60 years
Ecosystem should be correct sorry if I am wrong
75% species go extinct to be considered a mass extinction
Explanation:
when those components become excessive, they become harmful
