Which of the following is closest in meaning to the word "introverted" (Line 1, Para. 1)

A．running his father's cable-television business while still a student
B．putting together the largest cellular company in the country
C．selling his company to AT＆ T for $13 billion
D．doing sort of warm-up exercises every morning

A．he does not get on with the executives around him
B．he is jealous of others' great achievements
C．he is concerned with his own thoughts and feelings
D．he does not like others to talk about himself