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: A

Rationale: The BCG vaccine, which is used for tuberculosis, is known to leave a permanent scar at the site of injection. This distinctive scar formation is one of the characteristic features of receiving the BCG vaccine and is used as a marker of vaccination in some regions.

Correct Answer: B

Rationale: Children with measles are given vitamin A to prevent complications, such as blindness. Vitamin A supplementation is crucial in reducing the severity and risk of complications associated with measles, particularly in populations with vitamin A deficiency.

Correct Answer: B

Rationale: The correct answer is OPV. Oral Polio Vaccine should be stored in the freezer to maintain its potency. Vaccines like DPT, Hepatitis B vaccine, and Measles vaccine are typically stored in the refrigerator to ensure their efficacy.

Correct Answer: B

Rationale: A survey, specifically a sample survey, is the most appropriate method for gathering data about a sample of the population. In this scenario, focusing on families with members who are part of the target population for PEM requires collecting specific data from a subset of the overall population, making a survey the best choice for this purpose.