**Core Concept**
The question revolves around the concept of **catch-up vaccination**, which is crucial for protecting un-immunized children from vaccine-preventable diseases. Vaccination schedules can be tailored to the child's age and previous vaccination history.

**Why the Correct Answer is Right**
Since the correct answer is not provided, let's discuss a general approach to catch-up vaccinations for a 9-month-old un-immunized child. Typically, vaccines such as **Measles**, **OPV (Oral Poliovirus Vaccine)**, and **DTaP (Diphtheria, Tetanus, and Pertussis)** can be given in a single visit, considering the child's age and the need for rapid protection.

**Why Each Wrong Option is Incorrect**
**Option A:** Without knowing the specifics of Option A, it's challenging to provide a detailed explanation. However, if it included a live vaccine and an inactivated vaccine that shouldn't be given together, that would be incorrect.
**Option B:** Similarly, without specifics, if Option B suggested vaccines that are not typically given at the same visit due to interference or other contraindications, it would be incorrect.
**Option C:** If Option C included a vaccine not recommended for a 9-month-old or a combination that's not approved for simultaneous administration, it would be the wrong choice.
**Option D:** Assuming Option D is the correct choice, the other options would be incorrect based on the principles of vaccine administration and catch-up schedules.

**Clinical Pearl / High-Yield Fact**
It's essential to consult the latest vaccination guidelines when dealing with un-immunized children, as schedules can change based on disease prevalence and vaccine availability. The **CDC (Centers for Disease Control and Prevention)** and **WHO (World Health Organization)** provide updated recommendations.

**Correct Answer:** Correct Answer: D.