## Core Concept
The core concept here revolves around the immunization schedule, particularly for Oral Poliovirus Vaccine (OPV) and Diphtheria, Pertussis, and Tetanus (DPT) vaccine. Understanding the typical immunization schedule and the characteristics of these vaccines is crucial.

## Why the Correct Answer is Right
The correct approach involves continuing the immunization series with the next doses of OPV and DPT according to the recommended schedule. Typically, the OPV is given at birth, 6 weeks, 10 weeks, and 14 weeks of age, with a booster at 18 months. The DPT vaccine is usually administered in a series of three doses at 6, 10, and 14 weeks of age, followed by boosters. Given that the infant has already received the first dose of OPV and DPT, the next step would be to administer the subsequent doses as per the schedule.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because it does not specify what action to take, making it an incomplete choice.
- **Option B:** Without specifics, this option cannot be evaluated directly, but if it suggests stopping or altering the schedule without a valid reason, it would be incorrect.
- **Option C:** Similar to Option A, if this option does not align with the standard immunization protocol or suggests an inappropriate action, it would be incorrect.

## Clinical Pearl / High-Yield Fact
A key point to remember is that vaccines should be administered according to the national immunization schedule, and it's essential to check the vaccine history of the child before giving any vaccine to avoid over-immunization or under-immunization. For OPV and DPT, booster doses are critical for long-term immunity.

## Correct Answer Line
**Correct Answer: D.**