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
Fireflies produce light due to - 
Select and explain. 
A. NADH, B. GTP, C. ATP, D. Phosphocreatinine
C: ATP
Answer: C: ATP 
Explanation: Bioluminescence is light produced by a chemical reaction within an organism.
It requires a combination of 4 different ingredients. The light is produced through a chemical reaction involving Luciferin (which is the substrate), Luciferase (the enzyme), ATP and oxygen.
The basic reaction sequence is: The luciferase catalyzes the oxidation of luciferin into oxyluciferin. In the process, light is emitted.