Final answer:
b. Aliasing does not occur with power Doppler, which is NOT a reason a sonographer would choose to use it during a renal duplex exam.
Step-by-step explanation:
The reason a sonographer would NOT choose to use power Doppler during a renal duplex exam is because b. aliasing will not occur with power Doppler.
Aliasing refers to the effect where the frequency of the blood flow exceeds the maximum measurable velocity of the Doppler system, causing inaccurate or distorted measurements. Power Doppler does not provide velocity information and therefore does not produce aliasing artifacts.