**Core Concept**
The trivalent oral polio vaccine (OPV) is a live, attenuated vaccine used to protect against poliomyelitis, a highly infectious disease caused by the poliovirus. The vaccine contains three different strains of the poliovirus: types 1, 2, and 3.

**Why the Correct Answer is Right**
The trivalent OPV contains type 3 virus as one of its components. This means that the vaccine contains a weakened form of the type 3 poliovirus, which helps to stimulate the immune system and provide immunity against the disease. The type 3 virus in the vaccine is attenuated, meaning it has been weakened so that it cannot cause poliomyelitis, but still triggers an immune response.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not specified, so we cannot provide an explanation.
**Option B:** This option is not specified, so we cannot provide an explanation.
**Option C:** This option is not specified, so we cannot provide an explanation.
**Option D:** This option is not specified, so we cannot provide an explanation.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the trivalent OPV has been replaced by the bivalent OPV (bOPV) in many countries, which contains types 1 and 3 polioviruses, as the global effort to eradicate polio has shifted focus to these two remaining types.

**Correct Answer:** D. (Note: The correct answer is missing from the provided options)