**Core Concept**
Venomous snakes of the cobra family (Elapidae) are found in tropical coastal regions, and their venom contains neurotoxins that can cause respiratory failure.

**Why the Correct Answer is Right**
Sea snakes, specifically the genus *Aipysurus* and *Lapemis*, are a group of highly venomous marine snakes that are found in the coastal waters of the Indo-Pacific region. They are characterized by their slender bodies, flat heads, and vertical pupils. Sea snakes are ectothermic, meaning they regulate their body temperature using external sources, and are adapted to living in the marine environment. Their venom is a complex mixture of neurotoxins and hemotoxins that can cause severe pain, respiratory failure, and renal failure in humans.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct genus or species of sea snakes. There are several species of venomous snakes that are found in tropical coastal regions, but not all of them are classified as sea snakes.

**Option B:** This option is incorrect because it does not accurately describe the venom composition of sea snakes. While sea snake venom does contain hemotoxins, it is primarily composed of neurotoxins that can cause respiratory failure.

**Option C:** This option is incorrect because it does not accurately describe the habitat of sea snakes. While sea snakes are found in coastal waters, they are not exclusively marine animals and can be found in brackish and freshwater environments as well.

**Clinical Pearl / High-Yield Fact**
Sea snake bites are rare in humans, but can be life-threatening due to the potency of their venom. Prompt medical attention is essential in cases of sea snake bites, and patients should be treated with antivenom and supportive care.

**Correct Answer:** D.