Question

use the types of observational studies flow chart interactive to answer the following question. which one of the following is not an observational study? choose the correct answer below. a. randomly selected cigarettes are tested for the amounts of nicotine that they contain. b. randomly selected automobile seatbelts are tested for their breaking points. c. randomly selected robes are coated with a flame retardant and then tested for flammability. d. randomly selected airline pilots are asked about their flying experience.

Explanation:

An observational study observes or measures without interfering. In option C, robes are coated with a flame retardant (an intervention), so it's an experiment, not observational. A: testing nicotine in cigarettes (observing). B: testing seatbelt breaking points (observing). D: asking pilots (observing).

Answer:

C. Randomly selected robes are coated with a flame retardant and then tested for flammability.