**Core Concept**
The question is testing the characteristic features of poisonous snakes, specifically their venom composition and delivery mechanisms. Poisonous snakes, also known as venomous snakes, possess specific anatomical and physiological traits that enable them to deliver their venom to their prey or victims.

**Why the Correct Answer is Right**
Poisonous snakes have evolved unique features such as hollow, grooved fangs that deliver the venom into the bloodstream or tissues of their victims. The venom itself is a complex mixture of bioactive molecules, including enzymes, peptides, and proteins, that work synergistically to immobilize and kill their prey. The delivery of venom is facilitated by the snake's highly developed venom glands, which are capable of producing large quantities of venom.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not a characteristic feature of poisonous snakes. While many poisonous snakes have a distinctive color pattern or body shape, this is not a universal feature of all poisonous snakes.
**Option B:** This option is incorrect because it is a characteristic feature of poisonous snakes. The presence of hollow, grooved fangs is a hallmark of venomous snakes, which enables them to deliver their venom effectively.
**Option C:** This option is incorrect because it is a characteristic feature of poisonous snakes. The venom glands of poisonous snakes are highly developed and capable of producing large quantities of venom.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the venom composition and delivery mechanisms of poisonous snakes can vary greatly between species, with some snakes possessing highly toxic venom and others possessing more hemotoxic venom.

**Correct Answer: D.**