Biology question about otters

Which of these serves as a reference for comparison during a scientific investigation? a)outcome variable (dependent variable) b) test variable (independent variable) c)control group d)hypothesis

Apatient has an open displaced fracture of the second cervical vertebra. this is her fifth visit and the fracture is healing normally. what icd-10-cm code is reported?

18. over time, how do sand dunes tend to migrate? a. perpendicular to the movement of the wind b. in the same direction as the wind blows c. toward the wind d. in random directions