Final answer:
In an ECG test, electrodes should be placed on skin that is clean, dry, and not scarred, while hairy skin should be avoided or shaved to ensure proper contact and signal quality.
Step-by-step explanation:
When choosing a site to place electrodes for an ECG test, the site should be all of these things except C) Hairy. A clean, dry, and non-scarred skin surface is ideal for placing ECG electrodes to ensure good electrical contact and to reduce the likelihood of motion artifacts or poor signal quality. Hair can interfere with the electrode's ability to make proper contact with the skin, potentially causing a poor quality ECG reading. Therefore, sites with excessive hair may need to be shaved before electrode placement. However, if the skin is scarred, it may also affect the ECG signal due to the scar tissue altering the electrical conductivity through the skin.