An ionic bond $P^{+} Q^{-}$ is most likely to be formed when

• A
  the ionization energy of $P$ is high and the electron affinity of $Q$ is low
• B
  the ionization energy of $P$ is low and the electron affinity of $Q$ is high
• C
  the ionization energy of $P$ and the electron affinity of $Q$ is high
• D
  the ionization energy of $P$ and the electron affinity of $Q$ is low