A 5-Month-Old Infant Is Brought to the Pediatrician's Office, and the Nurse

A 5-month-old infant is brought to the pediatrician's office, and the nurse is collecting information from the mother. The mother reports the infant is irritable, eats poorly, and is less active. The nurse identifies tachycardia and a systolic murmur. Which comment by the mother helps the nurse identify the infant's condition?

A) "I am pleased that he sleeps well at night."
B) "Up until recently he was a happy baby."
C) "Formula made him gassy and constipated."
D) "He has not been what I call really sick."