I need help on this question

If w( t) is the rate of growth of a child in pounds per year, what does ( w (t) at represent? A. The increase in the child's weight (in pounds) between the ages of 5 and 10. B. The rate of growth of the child (in lbs/year) during his/her first five years of life. C. The rate of growth of the child (in lbs/year) between the ages of 5 and 10 D. The increase in the child's weight (in pounds) during his/her first five years of life