69. At sufficiently low temperatures, gaseous ammonia has a molar volume that is less than that predicted by the ideal gas law at certain low pressures, but has a molar volume that is greater than that predicted at certain high pressures. Which of the following is a reasonable explanation for this behavior? (A) Attractive forces predominate at these low pressures, and repulsive forces predominate at these high pressures. (B) Repulsive forces predominate at these low pressures, and attractive forces predominate at these high pressures. (C) Repulsive forces operate over greater distances than attractive forces. (D) As the pressure of a gas increases, its temperature increases. (E) Hydrogen bonding is not a factor at the critical pressure.