题目

Heather Jack and her family, including her two children, usually spend the Christmas holidays preparing a feast—for others to eat. Last Christmas Eve, they went to a house in the neighborhood and prepared a dinner for an elderly woman and her son, who has muscular dystrophy（肌肉萎缩症）. They stayed for an hour and chatted before heading home to prepare for a visit from Santa (圣诞老人). “I think it is that kind of direct experience that many find so meaningful,” says Heather, president and founder of The Volunteer Family, a Boston-based organization dedicated to mati是虚数单位，复数等于（ ）A．1+3iB．1-3iC．D．