The correct answer is C evolution
Answer:

Explanation:
We are asked to find how much of a 40 gram sample remains after 12 years.
Iron-55 has a half-life of 3 years. Therefore, after 12 years, 4 half-lives have been completed.
- 12 years/3 years = 4 half-lives
Every time a half-life is completed, half of the sample's mass decays. Remember we start with a 40 gram sample.
- 1 half- life: 40 g / 2 = 20 g
- 2 half-lives: 20 g / 2= 10 g
- 3 half-lives: 10 g / 2 = 5 g
- 4 half-lives: 5 g / 2 = 2.5 g
There is also a formula that can be used to solve this problem.

Where A₀ is the initial amount, t is the time, and hl is the half-life.
We know 40 grams is the inital amount, 12 years is the time, and 3 years is the halflife.




After 12 years, <u>2.5 grams </u> of Iron-55 will remain.
In a ecological pyramid, when we move up energy decreases by 10% at each step 'cause they get lost as "Heat" when energy flows from one Trophic level to another.
Hope this helps!
19. B - mitochondria
20. D - vegetative structure
21. C - inducing a mutation
22. A - phosphates
23. C - fungi
24. A - provides support
25. C - sponges
26. B - opposite charges
27. D - asexual reproduction
28. not sure about this one sorry
29. D - all of the above
30. A - prevents ions and large molecules from passing through the membrane
The answer is a (4) I hope this helps out a bit