Correct Answer: A

Rationale: Presidential Decree (P.D.) 651 amended Republic Act (R.A.) 3753, specifically requiring the registration of births within 30 days from their occurrence. This amendment emphasizes the timely and accurate recording of vital statistics, which is crucial for legal and administrative purposes.

Correct Answer: D

Rationale: Sensitivity is the ability of a diagnostic test to correctly identify individuals with the disease. A test with high sensitivity will rarely give false negative results, as it will detect almost all positive cases. In the context of the given scenario, false negative results indicate that the test is lacking in sensitivity to pick up all cases of pulmonary tuberculosis, leading to some cases being missed.

Correct Answer: C

Rationale: The vastus lateralis muscle is the preferred site for intramuscular injections in infants due to its larger muscle mass and fewer major nerves and blood vessels, reducing the risk of injury or adverse effects.

Correct Answer: D

Rationale: To estimate the number of 1-4 year old children in a population, you can multiply the total population by the percentage of children in that age group. In this case, using the Philippine population composition as reference, which is about 11.5% for 1-4 year olds, the calculation would be 20,000 x 0.115 = 2,300 children.

Correct Answer: A

Rationale: The primary reason for giving iron supplementation to pregnant women is to prevent anemia. Anemia can have detrimental effects on both the mother and the developing fetus. Iron is essential for the production of red blood cells, and during pregnancy, the demand for iron increases to support the mother's increased blood volume and the developing fetus. Anemia in pregnancy can lead to complications such as preterm birth, low birth weight, and even maternal mortality. Therefore, ensuring adequate iron intake through supplementation is crucial to prevent these adverse outcomes.