The correct answer is "Serotonin-norepinephrine reuptake inhibitor (SNRI)." This is correct because venlafaxine functions by blocking the reuptake of both serotonin and norepinephrine, and thus is classified as a serotonin-norepinephrine reuptake inhibitor (SNRI). Venlafaxine is used to treat a number of conditions including depression, anxiety, panic attacks, and social phobia, among others. In addition to its anti-depressant properties, it is also useful in that it can provide the benefit of increased energy in some patients due to the norepinephrine reuptake inhibition (effectively increasing the effect of norepinephrine). 

Selective serotonin reuptake inhibition (SSRI) is incorrect because venlafaxine is an SNRI, not an SSRI. An example of an SSRI is fluoxetine.

Monoamine oxidase inhibition (MAOI) is incorrect because venlafaxine is an SNRI, not an MAOI. An example of an MAOI is phenelzine. 

An example of a GABA agonist is phenobarbital, a barbiturate. 

An example of a beta-adrenergic blocker is propranolol.

The correct answer is "aged cheeses." This is the correct answer because MAOI's, when combined with food or drink products containing the metabolite, tyramine, have the potential to cause serious adverse effects including hypertensive crisis. Tyramine is found most commonly in aged cheeses and cured meats. Thus, since this patient is taking an MAOI, she should be advised to avoid aged cheeses.

Carrots, beets, grapefruit juice, and green, leafy vegetables do not need to be avoided in patients taking MAOI's. 

The correct answer is "Dopamine D2 receptor antagonist." 

This is the correct answer, as haloperidol is a first-generation antipsychotic, also known as a typical antipsychotic medication, and functions by selectively antagonizing dopaminergic D2 receptors. Haloperidol is used to treat a number of conditions including schizophrenia, bipolar disorder (manic phase), acute psychosis, tics from Tourette syndrome, and delirium, among others. 

Increased efficiency of GABA receptor binding describes the mechanism of action of benzodiazepines, not haloperidol.

Selective serotonin reuptake inhibition does not describe the mechanism of action of haloperidol. This describes medications like fluoxetine and escitalopram.

Serotonin-norepinephrine reuptake inhibition does not describe the mechanism of action of haloperidol. This describes medications like venlafaxine and desvenlafaxine.

Norepinephrine-dopamine reuptake inhibition does not describe the mechanism of action of haloperidol. This describes medications like buproprion and methylphenidate.

The correct answer is "Antagonism of M1, M2, and M3 muscarinic acetylcholine receptors."

This is the correct answer because it accurately describes the way in which oxybutynin exhibits its anticholinergic properties, which help to relieve urinary frequency/urgency and bladder spasm. In patients with spastic bladder, oxybutynin exhibits its anticholinergic effects most significantly on the smooth muscle of the bladder detrusor muscle, which helps to treat the patients' symptoms associated with spasm of the muscle, which often manifests as urinary frequency or urgency, with or without urinary incontinence. 

Calcium-channel blockade does not describe the mechanism of action of oxybutynin. Verapamil and amlodipine are examples of calcium-channel blockers.

Beta-adrenergic blockade does not describe the mechanism of action of oxybutynin. Propranolol and esmolol are examples of beta-adrenergic blockers.

Alpha-adrenergic blockade does not describe the mechanism of action of oxybutynin. Tamsulosin and doxazosin are examples of alpha-adrenergic blockers.

Direct thrombin inhibition does not describe the mechanism of action of oxybutynin. Argatroban and lepirudin are examples of direct thrombin inhibitors.