**Core Concept**
The SALK vaccine is a type of inactivated poliovirus vaccine (IPV) that provides immunity against poliomyelitis by inducing neutralizing antibodies against the poliovirus. It is primarily administered intramuscularly and is known for its effectiveness in preventing polio.

**Why the Correct Answer is Right**
Option C states that the SALK vaccine is contraindicated in immunocompromised patients. This is incorrect because inactivated vaccines like SALK are generally safe for individuals with weakened immune systems, including those with HIV/AIDS or undergoing chemotherapy. In fact, immunocompromised patients may benefit from vaccination to prevent infections, as they are more susceptible to severe outcomes.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is true. The SALK vaccine has been shown to be highly effective in preventing polio and its associated paralysis.

**Option B:** This statement is true. The oral poliovirus vaccine (OPV) can be given as a booster dose to individuals who have already received the SALK vaccine. OPV provides mucosal immunity and can help prevent poliovirus transmission.

**Option D:** This statement is true. The SALK vaccine is relatively stable and can be easily transported, making it a convenient option for vaccination campaigns and programs.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the SALK vaccine is not to be confused with the oral poliovirus vaccine (OPV), which is a live, attenuated vaccine. While OPV provides mucosal immunity and can help prevent poliovirus transmission, it carries a small risk of vaccine-associated polio.

**✓ Correct Answer: C. It is contraindicated in immunocompromised patients**