**Core Concept**
The question is testing knowledge of the Universal Immunization Programme (UPI) vaccines and their indications, specifically the vaccine that aims at preventing blindness. The correct answer involves a vaccine that targets a common cause of preventable blindness.

**Why the Correct Answer is Right**
The correct vaccine in the UPI that aims at preventing blindness is the **Measles vaccine**. Measles is a highly contagious viral infection that can cause serious complications, including blindness, in individuals who contract the disease. The measles vaccine is effective in preventing measles infection and its complications, including blindness. The measles vaccine works by inducing immunity against the measles virus, thereby preventing infection and its associated complications.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the question and does not have a vaccine that aims at preventing blindness.
* **Option B:** This option is not a vaccine and does not have a role in preventing blindness.
* **Option C:** This option is not a vaccine in the UPI that aims at preventing blindness.

**Clinical Pearl / High-Yield Fact**
Measles vaccine is a live attenuated vaccine that is given to children as part of the UPI, and it is effective in preventing measles infection and its complications, including blindness. It is essential to vaccinate children against measles to prevent this preventable cause of blindness.

**Correct Answer:** D. Measles vaccine