Answer: Tolerance
Explanation: Tolerance is an adaptive behavior whereby the body systematically adjusts in accordance to a certain behavior, custom or values. Psychological tolerance may develop in human due to regular intake of certain addictive drugs, medications whereby an individual may need to increase the dosage or amount being consumed with time in other to yield the same effect as before.
In the question above, Henry's system has successfully been able to tolerate six bottles without getting intoxicated and therefore needs to increase his alcohol intake to 12 bottles before getting intoxicated.