Little Susie has been a very easy baby to love, since she smiles at everyone who holds her and engages them with eye contact. Recently, however, Susie has become anxious when anyone other than her mother or father holds her, and she wails whenever she is picked up by a stranger. Based on a knowledge of child development, your best guess is that Susie is about how old:
◦ 4 months old
◦ 7 months old
◦ 13 months old
◦ 22 months old