**Core Concept**
Oxygen therapy is a crucial intervention in various clinical scenarios, particularly those involving poisoning or overdose with certain substances. The specific antidotal effects of oxygen in these situations are rooted in its ability to modulate cellular respiration, reduce oxidative stress, and mitigate the toxic effects of certain substances.

**Why the Correct Answer is Right**
In cases of carbon monoxide (CO) poisoning, oxygen therapy is a lifesaving intervention. CO binds to hemoglobin with high affinity, forming carboxyhemoglobin (COHb) and reducing the capacity of hemoglobin to transport oxygen. Oxygen therapy helps to displace CO from hemoglobin, thereby increasing the delivery of oxygen to tissues. This is particularly important in the brain, where CO poisoning can cause significant morbidity and mortality. Additionally, oxygen therapy may also be beneficial in cases of cyanide poisoning, as it can help to increase the availability of oxygen for cellular respiration, thereby reducing the toxic effects of cyanide.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because oxygen is not typically used as an antidote for barbiturate poisoning. In fact, oxygen therapy may even worsen barbiturate-induced respiratory depression.
* **Option B:** This option is incorrect because oxygen is not a specific antidote for benzodiazepine poisoning. While oxygen therapy may be provided as part of supportive care, it does not have any direct antidotal effects.
* **Option C:** This option is incorrect because oxygen is not a specific antidote for aspirin poisoning. In fact, oxygen therapy may even worsen the risk of cerebral edema and other complications associated with aspirin overdose.

**Clinical Pearl / High-Yield Fact**
In cases of CO poisoning, the presence of cherry-red discoloration of the skin, lips, and mucous membranes is a classic sign, but it is not always present. A more reliable indicator of CO poisoning is a carboxyhemoglobin level of >10%, which can be measured using a co-oximeter.

**Correct Answer:** D.