Answer:
The energy of photon, 
Explanation:
It is given that,
Voltage of anode, 
We need to find the maximum energy of the photon of the x- ray radiation. The energy required to raise an electron through one volt is called electron volt.

e is charge of electron


So, the maximum energy of the x- ray radiation is
. Hence, this is the required solution.
I believe that answer is nitrogen.
C) is correct
series circuit - in the same path : current flow on one path so they are equal on each component and equal to the source's. voltage on each components may be different.
parallel circuit - between same nodes : voltage of the components are equal and equal to the source's. current on each components may be different.