Question

I just want to check my answers. Help go over them with me please to make sure they're right. Thank you.

Which of the following scenarios would be an attempt to quantify induced variability?

A. A phone survey of political preferences during election season
B. Multiple random samples of products from an assembly line to check for defects
C. Random assignment of people to a control group and a group taking a drug to lower cholesterol
D. Recording the variability in the measurement of a soil samples weight by the same machine

My answer is C