Final answer:
The sole reagent required for the Iodine Test for starch is 0.1 M potassium triiodide solution.
Step-by-step explanation:
The sole reagent required for the Iodine Test for starch is 0.1 M potassium triiodide solution. When iodine reacts with a mixture of starch and iodide ion, it forms a deep blue color, which is a very sensitive test for the presence of iodine in water.