Which causal relationship is justifiable?
a) children with bigger feet spell better. spelling better causes a child's feet to grow.
b) surf board sales rise when lemonade sales rise. drinking lemonade causes more people to buy surfing boards.
c) the traffic is heavier around the stadium when a game is being played. games being played cause more traffic.
d) an elementary school child has more cavities than his baby brother. he also has a larger vocabulary. an increased vocabulary causes cavities.