Stimulant or depressant drugs.
It's more accurate, especially since heart rate is almost universally measures in beats-per-minute, than, say, timing your pulse for a [factor of 60] seconds (30 seconds, 20 seconds, 15 seconds, 12 seconds, etc.).
Take him out to dinner. maybe wash his car, buy him a new puppy. compliment his shoes, compliment his dad sandals with white socks. tell him yes, his high school letter jacket DOES fit. buy him McDonalds. look deep into his eyes, and say
" if you were a man, you'd get some braces so you don't look like Bugs Bunny..."
The answer is B: Some patients who have a poor hospital experience also have post-surgical complications.
This because this can't be a cause and effect because it's a survey study, and only 40% of the people who have poor hospital experience also have post-surgical complications.