Mario is three. He likes to draw, but it is difficult to tell what he is drawing. He likes to talk about what he is doing and what he sees outside the window. His parents can understand about half of what he says. He is beginning to play with other children, but does not like to share his toys. Based on this information, which of the following would concern a doctor?

Mario's social skills
Mario's fine motor skills
Mario's speech
Mario's intelligence