Read the following passage and answer the question selecting the most appropriate alternative.
A four year study conducted by the Infant Testing Centre in San Francisco, California suggests that babies feel more comfortable around other babies than with strange adults. According to the study, babies benefit by being with their fellow infants daily. Whereas a baby might show fear of an adult stranger, he is likely to smile and reach out for an unfamiliar infant. By the time babies are one year old, they have begun to form friendship of a sort. The above findings based on abservation of 100 babies aged three months to three years, might prove interesting to working parents who have to find day care for their babies. Family care in a private home, with several babies together, is probably the ideal way to care for babies under three. Dr. Benjamin Spock well known Paediatrician and author of books about babies, supports the idea. He says that family day care is sounder in theory than hiring a housekeeper or a baby sitter.