Comprehensive and Detailed Explanation From Exact Extract (No URLs):

According to AWHONN’s Fetal Assessment Text, Simpson & Miller, and Menihan, vibroacoustic stimulation is utilized during NSTs to elicit fetal accelerations, thereby minimizing testing time.

NCC-referenced sources describe VAS as:

• A method that awakens the fetus,

• Stimulates the fetal auditory system,

• Produces reactive accelerations in a neurologically intact fetus,

• Dramatically shortens NST duration, especially when the fetus is in a sleep cycle.

VAS does NOT measure amniotic fluid, nor does it have any effect on uterine activity (therefore cannot treat tachysystole).

The only correct purpose supported by NCC-cited literature is that VAS shortens the duration of the NST, making Option C correct.