Steam distillation is a separation technique used for purifying organic compounds that are immiscible with water and have high boiling points. In this method, the organic compound co-distills with water. The key concept here is that the total vapor pressure of the mixture is the sum of the vapor pressures of the organic compound and water. When the total vapor pressure equals atmospheric pressure, the mixture will boil.

For a compound that has a boiling point of $$250^{\circ} \mathrm{C}$$ and is immiscible with water, during steam distillation, the boiling point of the mixture will be influenced by both the vapor pressure of water and the organic compound. Since water has a boiling point of $$100^{\circ} \mathrm{C}$$, steam distillation allows the mixture to boil at a temperature lower than the boiling point of the organic compound when in pure form. This is because the partial pressures of both the water and the organic compound add up to reach the atmospheric pressure more quickly than either would alone.

Practically, the mixture will boil at a temperature close to the boiling point of water, which is $$100^{\circ} \mathrm{C}$$. Hence, the correct answer is:

Option D close to but below $$100^{\circ} \mathrm{C}$$