Ralph Used to Get Quite a "Buzz" from a Single

Multiple Choice

Ralph used to get quite a "buzz" from a single cup of coffee.Now he finds that he can drink up to four cups without even noticing the effects of the caffeine.This would suggest that Ralph:

A) has developed a drug dependency on caffeine
B) has developed a drug tolerance for caffeine
C) is experiencing the effects of drug withdrawal
D) will probably develop an allergic reaction to caffeine