Which of the following is a synonym for methamphetamine?

Methamphetamine is commonly known by various street names, two of which are "speed" and "crystal meth." Both of these terms refer to the same substance - methamphetamine. "Speed" typically refers to the powdered form of methamphetamine, which is often inhaled, whereas "crystal meth" refers to the crystalline form that is usually smoked. The use of both names in common parlance indicates that they are synonyms for the drug in question.

On the other hand, hashish is a completely different substance derived from cannabis and is not related to methamphetamine. Therefore, recognizing that both "speed" and "crystal meth" are valid terms for methamphetamine clarifies why the correct answer encompasses both.