**Core Concept**
Reproductive and Child Health (RCH) is a government program aimed at improving maternal and child health in India. RCH Phase 1 and Phase 2 are two distinct phases with different objectives and interventions. RCH Phase 2 is focused on strengthening the existing RCH program, improving health services, and enhancing access to quality care.

**Why the Correct Answer is Right**
RCH Phase 2 focuses on various interventions such as immunization of pregnant women, treatment of Sexually Transmitted Diseases (STDs) and Reproductive Tract Infections (RTIs), and early registration of pregnancy up to 12-16 weeks. However, "Feed to malnourished children" is not a part of RCH Phase 2. This intervention is more closely related to the Integrated Child Development Services (ICDS) program, which provides supplementary nutrition to children and pregnant women.

**Why Each Wrong Option is Incorrect**
**Option A:** Immunization of pregnant women is indeed a part of RCH Phase 2, which aims to improve maternal and child health by providing essential vaccinations.
**Option B:** Treatment of STD/RTI is also included in RCH Phase 2, as it is crucial for preventing the spread of infectious diseases and promoting reproductive health.
**Option C:** Early registration of pregnancy up to 12-16 weeks is another key component of RCH Phase 2, which enables timely prenatal care and improves maternal outcomes.

**Clinical Pearl / High-Yield Fact**
It is essential to note that RCH Phase 2 also focuses on improving access to quality care, enhancing health infrastructure, and strengthening health systems. This phase aims to reduce maternal and child mortality rates, as well as improve overall reproductive and child health outcomes.

**✓ Correct Answer: D. Feed to malnourished children**