A. Glucose and salts
Solution
During urine formation, useful substances are taken back into the blood from the kidney tubules. This process is called tubular reabsorption.
Glucose and salts are useful substances, so they are reabsorbed by the kidneys and returned to the blood.

Glucose → reabsorbed because it is needed by the body for energy.
Salts → reabsorbed because the body needs them for various functions and to maintain the proper salt-water balance.
Starch and glycogen → are not normally present in the filtrate because they are large carbohydrates.