Final answer:
(1) Whole wheat bread is most likely to have the highest fiber content because it is made from whole grains that include the bran, which is rich in fiber. White bread, made from refined grains, and sourdough, typically made with white flour, have lower fiber content. Multigrain bread may vary in fiber content depending on the grains' refinement.
Step-by-step explanation:
Among the types of bread listed, whole wheat bread is MOST likely to have the highest fiber content. Whole wheat bread is made from whole grains that contain all parts of the grain kernel, including the bran, germ, and endosperm. Since fiber is found in the bran, whole grain breads inherently have more fiber.
In contrast, white bread is made from refined grains that have had the bran and germ removed, which significantly lowers its fiber content. Multigrain bread might also be a good source of fiber, particularly if it is made with whole grains, but it can vary depending on whether the grains used are whole or refined. Sourdough bread is typically made with white flour and is not a significant source of fiber.
The Mayo Clinic and other medical authorities recommend adding fiber-rich products like whole grain bread to our diets for their health benefits, which include reduction in risks of coronary heart disease, colon cancer, and type 2 diabetes. Therefore, choosing whole grain breads over refined ones is a healthier option for increasing fiber intake.