n an experiment, the researcher, Dr. Chalk, knows which group subjects have been assigned too. Each time a participant gets close to the answer that supports the hypothesis, Dr. Chalk gives a head nod without realizing it. This is an example of the effect.

Answer: pathogensstep by step solution:

Smoking damages the respiratory system by inhalation of a foreign substance, that is absorbed and residue is left behind on our lungs sponge like substance. the gas that is inhaled also increase your blood pressure and dilates your blood vessels. also the process of inhaling and exhaling the smoke it causes irritation to the throat and mouth. smoking can cause lung cancer and other respiratory and circulatory diseases.