(2) all this labeling can be overwhelming. (3) this is why so many people scratch their heads as they try to figure out the difference between natural and organic products.

without changing the meaning, which of the following best combines sentences 2 and 3?

a.
all this labeling can be overwhelming; therefore, folks in supermarkets all around the world get frustrated as they try to figure out the difference between natural and organic products.
b.
all this labeling can be overwhelming, so this is the exact reason why so many customers scratch their heads as they try to figure out the difference between natural and organic products.
c.
considering all food is labeled, people in supermarkets scratch their heads as they try to figure out the difference between natural and organic peanut butter.
d.
because food labels can be overwhelming, shoppers often scratch their heads as they try to figure out the differences between natural and organic products.