Final answer:
Masking refers to shadowing caused by mechanical prosthetic valvular apparatus in echocardiography, obstructing Doppler signal and proper visualization of blood flow.
Step-by-step explanation:
The term that refers to shadowing caused by mechanical prosthetic valvular apparatus, which inhibits flow display on a color doppler image, is B) Masking. In medical imaging, particularly in echocardiography, masking occurs when the prosthetic material of a mechanical valve creates acoustic shadows that obstruct the Doppler signal, preventing proper visualization of blood flow. This can be challenging for clinicians as it can lead to difficulty in assessing valvular function and flow dynamics around the prosthetic valve.