That's "<em><u>insolation</u></em>" ... not "insulation".
'Insolation' is simply the intensity of solar radiation over some area.
If 200 kW of radiation is shining on 300 m² of area, then the insolation is
(200 kW) / (300 m²) = <em>(666 and 2/3) watt/m²</em> .
Note that this is the intensity of the <em><u>incident</u></em> radiation. It doesn't say anything
about how much soaks in or how much bounces off.
Wait !
I just looked back at the choices, and realized that I didn't answer the question
at all. I have no idea what "1 sun" means. Forgive me. I have stolen your
points, and I am filled with remorse.
Wait again !
I found it, through literally several seconds of online research.
1 sun = 1 kW/m².
So 2/3 of a kW per m² = 2/3 of 1 sun
That's between 0.5 sun and 1.0 sun.
I feel better now, and plus, I learned something.
A group of protons and neutrons surrounded by electrons
The only balanced equation is B. If you look at the equation and break it down you can see that in:

→

Starting from the left side of the equation there are 2 Nitrogen atoms, and 2 oxygen atoms as indicated by the subscript.
To balance the equation, the number of atoms of each element in the right side equation should be equal to left. By putting the numerical coefficient of 2, you will distribute that to each element. So you will end up with 2 nitrogen atoms and 2 oxygen atoms on the left side of the equation. Thus, the equation is balanced.
The answer again, is B.