How did the author feel when she saw her children searching under the Christmas tree for their presents

A．I love the pearl necklace you bought me for my birthday
B．it must have taken you a long time to find just the right thing for me
C．is it very expensive
D．I promise I will wear it on my wedding day

A．She feels hand-written letters are friendlier than word-processed ones.
B．She does not allow her children to send email thank-you note.
C．She thinks the best time to teach her children the basic etiquette of appreciation is to strike while the iron is still hot.
D．She thinks a thank-you note can make the gift giver feel special just as the recipient does.