Raisins are made by drying grapes in the sun. Although some of the sugar in the grapes is caramelized in the process, nothing is added. Moreover, the only thing removed from the grapes is the water that evaporates during the drying, and water contains no calories or nutrients. The fact that raisins contain more iron per calorie than grapes do is thus puzzling. Which one of the following, if true, most helps to explain why raisins contain more iron per calorie than do grapes? ['The body can absorb iron and other nutrients more quickly from grapes than from raisins because of the relatively high water content of grapes.', 'Raisins are often eaten in combination with other iron-containing foods, while grapes are usually eaten by themselves.', 'Since grapes are bigger than raisins, it takes several bunches of grapes to provide the same amount of iron as a handful of raisins does.', 'Caramelized sugar cannot be digested, so its calories do not count toward the calorie content of raisins.']