This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ULTRASOUND, Subject name: Radiology
Evaluation of cardiac valve motion and fetal hea rate is done in which mode of Ultrasound? 
Select and explain. 
A. A-mode, B. B-mode, C. M-mode, D. D-mode
C: M-mode
Answer: C: M-mode 
Explanation: M-Mode Ultrasound is Motion mode and is used to evaluate Fetal Hea Rate and Cardiac Valve movement and echocardiography. Also used for detection of pneumothorax. A Mode Ultrasound is Amplitude Mode for measuring Axial length of Eyeball and orbital biometry (A scan in Opthalmology is the A Mode Ultrasound) B Mode Ultrasound is most commonly used mode. It is Brightness mode for routine Ultrasound. M Mode used in antenatal scan to calculate feral hea rate.