<prompt> During 3rd day to 2nd week of starvation, brain depends on which of the following substance as fuel:Ketone bodiesGlucoseFatty acidAmino Acid  <response>: For brain, Glucose is the mainpreferred fuel during Fed as well Fasting state whereas during Starvation, Brain depends upon Ketone Bodies as the fuel. So, answer is A - Ketone bodies. ADDITIONAL EDGE: Fed state: When we eat food Within 2 hours of food intake is called Fed state Fasting state: In between meals, when we are not eating food From 12-18 hours after food upto 48 hours is Fasting Starvation: Severe or complete lack of nutrients since last 1-3 days In between meals and night time is called Fasting time. Thats why Breakfast is named --BREAK THE NIGHT FAST. 