If the triple point pressure of a substance is greater than 1 atm, which two of the following conclusions are valid?

(a) The solid and liquid states of the substance cannot coexist at equilibrium.

(b) The melting point and boiling point of the substance are identical.

(c) The liquid state of the substance cannot exist.

(d) The liquid state cannot be maintained in a beaker open to air at 1 atm pressure.

(e) The melting point of the solid must be greater than 0 °C.

(f) The gaseous state at 1 atm pressure cannot be condensed to the solid at the triple point temperature.