Which statement is correct? a. The social smile in response to another person first appears at about 12 weeks old. b. Very young infants seem incapable of expressing distress and contentment. c. A 5-month-old baby is likely to display fear of strangers and separation anxiety. d. An 11-month-old girl may show anxiety when her mother goes into another room.

The correct option is D: An 11-month-old girl may show anxiety when her mother goes into another room.

Explanation:

Option C is wrong because: A 5 month old baby will not develop fear of strangers and separation anxiety because it is between the age of 4 to 6 months that they begin to develop vision, which means that they may not have the ability to distinguish between their mother and strangers.

Option B is wrong because Young infants begin to experience distress and contentment even before they are 12 months.

Option A is wrong because at 12 weeks, which is 3 months, the baby still uses sound and not facial expression. Hence at, three months, a baby is more likely to smile to a sound from a person rather than in response to a smile.

The correct option is D: At 11 months, a baby's vision is clear and can differentiate between his parents and others, and at this point they begin to show some emotions like anxiety, fear and others.