Which of the following is the best definition of longitudinal wave?

in a longitudinal wave, particle displacement is above the direction of wave motion.

in a longitudinal wave, particle displacement is opposite to the direction of wave motion.

in a longitudinal wave, particle displacement is parallel to the direction of wave motion.

in a longitudinal wave, particle displacement is perpendicular to the direction of wave motion.

This patient undergoes a gallbladder sonogram due to epigastric pain. the report indicates that the visualized portions of the liver are normal. no free fluid noted within morisons pouch. the gallbladder is identified and is empty no evidence of wall thickening or surrounding fluid is seen there is no ductal dilation. the common hepatic duct and common bile duct measure 0.4 and 0.8 cm respectively. the common bile ductmeasurement is at the upper limits of normal what cpt code in icd-10 cm code was used