**Core Concept**
Polyvalent snake vaccines are designed to provide immunity against multiple species of venomous snakes. These vaccines typically contain a mixture of immunoglobulins or antigens derived from various snakes, aiming to neutralize the venom's toxic effects.

**Why the Correct Answer is Right**
The polyvalent snake vaccine primarily contains immunoglobulins against species like Indian cobra (Naja naja), common krait (Bungarus caeruleus), Russell's viper (Daboia russelii), and saw-scaled viper (Echis carinatus). However, it does not contain immunoglobulins specifically against the saw-scaled viper, as this species is often targeted by a monovalent vaccine.

**Why Each Wrong Option is Incorrect**
**Option A:** Indian cobra - This species is typically covered by the polyvalent snake vaccine, so it's not the correct answer.
**Option B:** Common krait - Like the Indian cobra, the common krait is also a target of the polyvalent snake vaccine.
**Option C:** Russell's viper - This species is also included in the polyvalent snake vaccine, making it an incorrect option.
**Option D:** Saw-scaled viper - This is the correct answer, as the polyvalent snake vaccine does not contain immunoglobulins specifically against this species.

**Clinical Pearl / High-Yield Fact**
It's essential to note that while polyvalent snake vaccines are effective, they may not provide complete protection against all species of venomous snakes. Therefore, prompt medical attention is crucial in the event of a snakebite.

**Correct Answer: D. Saw-scaled viper**