Final answer:
The term for the amount of medication given is 'dose,' which is option D. 'Effective dose - 50%' is best described by option D, denoting a dose causing a significant response in 50% of subjects. The phenomenon of requiring increased amounts of a drug to achieve the same effect is known as 'tolerance.'
Step-by-step explanation:
The amount of medication that is given is known as the dose. The dosage refers to the amount of medication given during a certain time interval and it is vital to determine it carefully to achieve the best therapeutic effect without causing significant toxicity to the patient. The best dose is one that minimizes the risk of side effects while still achieving a clinical cure.
5. "Effective dose - 50%" describes the dose that results in a significant response in 50% of subjects, which is option D.
When a drug user requires more and more of a given drug to experience the same effects, this is referred to as tolerance, which is option c.