Answer:
D.
Step-by-step explanation:
Leaving your drink unattended would provide the opportunity for someone to slip a pill in it, taking drinks from strangers is dangerous because you did not see them pour it and it could already be drugged, and drinking a foaming and odd colored drink is dangerous because it is showing signs of being tampered with.
D. is the only safe answer in this scenario; throw away any drinks given to you by a stranger.
I hope that this helps you in the future, and that this can become common sense that will keep you safe.