Given a sentence containing a mention of substance use, consider the following categories:

ALPHA: Patient currently uses this substance.

BETA: Patient has used this substance at some point in the past. Maybe they have stopped, maybe not.

GAMMA: Patient denies using it.

DELTA: Discussion about substance or someone else using it other than the patient.

In the sentence “his alcohol cravings are lower”, "alcohol" falls under which category? Reply only with one word: ALPHA, BETA, GAMMA, or DELTA.