**Core Concept**
Growth during the second year of life is characterized by rapid increase in both length and weight. This period is marked by significant development of motor skills, cognitive abilities, and a substantial increase in the child's nutritional requirements.

**Why the Correct Answer is Right**
The rate of growth during the second year is approximately 4-5 inches in height and 4-5 pounds in weight per month. This accelerated growth is due to the child's increasing muscle mass, bone density, and overall energy expenditure. As the child becomes more active and mobile, their caloric needs increase to support this growth.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately represent the average growth rate during the second year of life.
**Option B:** This option is incorrect as it underestimates the average growth rate during the second year of life.
**Option C:** This option is incorrect as it overestimates the average growth rate during the second year of life.

**Clinical Pearl / High-Yield Fact**
The second year of life is a critical period for growth and development, and children during this period require adequate nutrition and regular healthcare check-ups to support their rapid growth and development.

**Correct Answer:** D. 5 inches in height and 5 pounds in weight per month.