Cocaine: a. Has no effect on the immune system. b. Exacerbates HIV replication in a mouse/human model of viral replication. c. Binds to the delta opioid receptor. d. Depresses IL-2 production. e. All of the above.

Carefully read through each option given in the exercise and try to recall the information related to the effects of cocaine on the immune system and its interactions with other substances. Make sure you have a clear understanding of each statement before evaluating them.

Based on your knowledge, evaluate each option to determine if it is true or false. Here are some key points: a. Cocaine has been reported to have effects on the immune system, impairing its functionality. Therefore, this option is false. b. Research has shown that cocaine can increase HIV replication in some models, so this option is true. c. Cocaine is known to act primarily as an inhibitor of monoamine transporters – specifically dopamine, norepinephrine and serotonin transporters – rather than binding to the delta opioid receptor. Therefore, this option is false. d. IL-2, or interleukin-2, is an important immune-regulating cytokine. Studies have shown that cocaine can depress IL-2 production, negatively affecting immune responses. Therefore, this option is true.

Based on the evaluations made in step 2, we have identified that options (b) and (d) are true. Now, taking a look at option (e) which states "All of the above," we can determine that this option is false, since we found options (a) and (c) to be false. Therefore, the correct answer is that cocaine: b. Exacerbates HIV replication in a mouse/human model of viral replication. d. Depresses IL-2 production.