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: Pediatrics
What is the instrument used for? 
Select and explain. 
A. Assessment of eye size, B. Stool assessment tool, C. Assess the volume of testicles, D. Growth assessment tool
C: Assess the volume of testicles
Answer: C: Assess the volume of testicles 
Explanation: The above image represents Orchidometer.
It helps to assess the volume of testicules.
Testicular size > 4cc in volume is the 1st sign of puberty in males.