Answer:
i am pretty sure it is calcium but don't quote me on that hope you get it right
you could also ask your teacher
Explanation:
The model changed to match the findings as new technology allowed. This is the correct answer.
Answer -
<em>The answer is below, one of the switches is open and the other one isn't needed so you just need to take it out as it shows below.</em>
<em>please let me know if I got it right :)</em>
<em>hope this helps <3</em>