This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fundamentals In Radiology, Subject name: Radiology
USG probe is made up of: 
Select and explain. 
A. Barium, B. Quartz, C. Sodium iodide, D. Diamond
B: Quartz
Answer: B: Quartz 
Explanation: Ans. b (Quartz) (Ref: A user's guide to diagnostic ultrasound by Shirley Cusick-XVI, Rumac Diagnostic Ultrasound Vol I, 2nd/pg.10)# The ultrasound probe or the transducer is any device that converts one form of energy to another. In case of ultrasound, the transducer converts electric energy to mechanical energy and vice versa.# The ultrasound transducer uses the principle or property of piezoelectricity, which occur naturally in some materials whereby an applied electric field produces a change in linear dimensions.- Quartz, a naturally occurring piezoelectric material having the unique ability to respond to the action of an electric field by changing shape and to the change in polarity of voltage applied by generating small potentials and thus producing an ultrasound image.- Lead Zirconate titanate is synthetic material with piezoelectric property, currently used in USG probes.