Babies Born with Low Birth Weights (Less Than 2500 Grams)

Babies born with low birth weights (less than 2500 grams) are at an increased risk for many infant diseases. Researchers in North Carolina collected data to see what variables may influence the birth weight (in grams) of a child, including whether the mother drank alcohol during pregnancy, whether the mother smoked during pregnancy, the mother's age (years) , the gestation of the pregnancy (number of weeks from conception until birth) , the mother's race, the length of the birth (hours) , and several others. The plot below summarizes some of the variables measured.
-Is whether the mother smoked during pregnancy a confounding variable in describing the relationship between gestation period and birth weight?

A) No, because smoking status is not associated with gestation period.
B) No, because smoking status is not associated with birth weight.
C) Yes, because mothers who smoke tend to have lighter babies, and mothers who smoke also tend to have shorter gestation periods.
D) Yes, because mothers who smoke tend to have heavier babies, and mothers who smoke also tend to have longer gestation periods.
E) We cannot determine whether smoking status is a confounding variable based on this plot.