Which of the following substances is a mixture of buprenorphine and naloxone?

Suboxone is the correct answer as it is a well-known medication that combines the active ingredients buprenorphine and naloxone. Buprenorphine is an opioid used for treating addiction to other opioids, while naloxone is an opioid antagonist that helps prevent misuse by blocking the effects of opioids if the product is tampered with by injection. The combination is specifically designed to support substance use disorder treatment while minimizing the potential for abuse.

The other substances listed do not contain this combination. Ketamine is primarily used as an anesthetic and has different pharmacological properties. Heroin is an illicit opioid that is not formulated with naloxone and poses significant risks of addiction and overdose. LSD is a hallucinogenic drug with entirely different effects and does not relate to opioid treatment. Thus, only Suboxone accurately represents the combination of buprenorphine and naloxone in a therapeutic context.