During the formation of which of the following ionic species, the process will be exothermic and endothermic respectively:

A

$$Na^+$$ and $$Cl^-$$

B

$$Cl^-$$ and $$O^{2-}$$

C

$$He^+$$ and $$Mg^{2+}$$

D

$$F^-$$ and $$Br^-$$