For most common anions of elements, extent of solvation (that is hydration):

for most commonly occurring element anions. The amount of solvation (or hydration) decreases over time.
A group's atomic size increases from top to bottom in accordance with an element's periodic properties. When an atom hydrates, energy is released in proportion to how attracted it is to the water molecules. An atom will attract more when it is smaller, which will cause more energy to be released. Hydration energy is the term used to describe this force. When atomic size increases, there is less attraction and less energy released during hydration.
Consequently, option B is the appropriate choice.