Over time, the body needs more and more of a drug to get the high that once came easily.
a. true
b. false

This is true. It's true because the body; or rather the receptors in our brain become accustomed to a certain amount of the drug and get adapted, they then later need a higher amount of this drug to achieve the same effect. This can also lead to overdosing over time. 

“d” is the answer to the question

The correct answer is "grounded".