At the beginning of spring, Dominic planted a small sunflower in his backyard. The sunflower's height in inches, hh, after ww weeks, is given by the equation h=19+3.5w . What could the number 3.5 represent in the equation?
a. The sunflower's final height
b. The sunflower's height when it was planted.
c. The sunflower's height after one week.
d. The change in the sunflower's height for every one additional week.