This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Fatty acids are the main source of energy for 
Select and explain. 
A. Muscles, B. Heart, C. Liver, D. RBC
B: Heart
Answer: B: Heart 
Explanation: Fed state Preferred fuel
Starvation preferred fuel




RBC


Glucose
Glucose




Heart


Fatty acids
Ketone bodies




Brain


Glucose
Ketone bodies




Liver


Glucose
Fatty acids / protein




Muscle


Glucose
Fatty acids




Adipose tissue


Glucose 
Fatty acids.