Which piece of evidence from the article MOST appeals to the reader's sense of emotion?

A. "If they knew the extent of the impact on this person, they would do it more often," Kumar says.
B. "They feel extremely positive when they were on the receiving end of these expressions," he says. "They don't really feel awkward at all."
C. Then they questioned both the writer and the recipient about that letter and how it made them feel.
D. Most of the students sent the letter by email. The researchers then contacted the recipients and asked about receiving the letter.