If health improvements occur rapidly in a country, why can the death rate decline?

Correct answer: Because disease prevention and treatment become better

Direct answer: B. Death rate measures deaths in relation to the population during a specified period. Health improvements can reduce deaths by preventing disease, detecting illness earlier and providing more effective treatment. Better vaccination, sanitation, medical care and access to health services can lower the risk that people die from preventable or treatable conditions. A is wrong because migration does not automatically reduce deaths and is not the basic reason for improved survival. C is wrong because a change in the meaning of birth rate has no direct connection with mortality. D is wrong because an increase in physical area does not itself make people healthier or reduce deaths. The actual change in death rate also depends on age structure and other conditions, but improved prevention and treatment are the central explanation here. Memory cue: prevention plus treatment can lower mortality.