Final answer:
Sudan stain would be the best option to visualize lipids. When a scientist uses Sudan Red dye to stain sections of a root and observes them under a microscope, they are likely to see staining in the sieve elements of the phloem caused by transported oil droplets.
Step-by-step explanation:
The best option to visualize lipids would be Sudan stain. Sudan Red dye is used to stain primarily waxy, hydrophobic material, such as lipids. When a scientist observes sections of a root stained with Sudan Red under a microscope, they are likely to see the sieve elements in the phloem showing staining due to transported oil droplets.