A Mother Was Very Proud That She Had Cut Back

A mother was very proud that she had cut back smoking from two packs a day,which she had smoked for years,to only half a pack a day.Which would be the most appropriate response by the nurse?

A) "I wish all smoking moms could see your example!"
B) "I'm so proud of you.You're down to only 25% of what you used to smoke!"
C) "That must have been difficult,but you're probably still getting nicotine,so it's important you quit entirely."
D) "Your baby will really appreciate your efforts at quitting,especially if you do not resume after the baby is born."