I dont know how to do this but i think maybe you would probably subtract.....
Answer:
B and D as well
Explanation:
All the electronic configuration of the elements of B end on s sub shell.
S energy level sub shell can hold 2 electrons and since Be, Mg, Ca Sr end in s.
We can say, they have same valence electrons, i.e 2 electrons.
The answer is caves.. i think
<span>Cost and availability of fuel is a considerable factor when dealing with nuclear power. Fission requires an element that can be easily split in a particle accelerator, such as uranium or plutonium. Fusion, on the other hand, uses isotopes of hydrogen atoms, specifically deuterium and tritium, that can be obtained from ordinary water</span>