a) Cumulus is 100% the correct answer
Hey
Potential Difference given is : 2V
Resistance is : 2 ohms
By Ohm's Law, one can easily utilize the relation :

Where, { v , i , r } are the potential difference, current and Resistance Respectively.
Hence,

Hence, the Current is 1 Ampere
Answer: This is the orbit (of the moon around Earth).
An orbit is a circular/oval path that planets, moons, comets, etc follow with a "subject" in the middle. In this case, the circle is the orbit of the moon around Earth.
It is very difficult for an atom to accept a proton. It can only be done under very special circumstances. So A and C are both incorrect. I don't see how D is possible. The atom does lose 1 electron, but how it gets 21 is think air.
The answer is B which is exactly what happens.