Two solid substances P and Q consist of atoms with masses $M_P$ and $M_Q$ respectively. They contain $n_P$ and $n_Q$ atoms in each unit volume. The density of P is higher than the density of Q. Which statement must be true?
- A$M_P > M_Q$
- B$n_P > n_Q$
- C$M_P n_P > M_Q n_Q$
- D$\dfrac{M_P}{n_P} > \dfrac{M_Q}{n_Q}$