Herd immunity occurs when a ___ proportion of a population has become immune to an infection — either through vaccination or prior illness — such that the disease can no longer spread efficiently. When enough individuals are immune, the pathogen has too few ___ hosts available to sustain transmission and its spread declines, protecting even those who cannot be vaccinated. The immunity ___ varies by disease: for measles, approximately 95 percent of the population must be immune to prevent outbreaks. Achieving ___ vaccination coverage is therefore essential not just for individual protection but for community-wide control of infectious disease.

Autonomous vehicles, which use sensors, cameras, and artificial intelligence to navigate without human input, have the potential to ___ a ___ proportion of road accidents caused by human error. Developers argue that self-driving technology could also ___ drunk driving and fatigue-related crashes. However, governments face the challenge of how to ___ a technology whose capabilities and limitations are still being established. Full deployment will also require investment in digital road ___ such as smart traffic management systems and high-precision mapping.

Traditional economic theory assumes that people are essentially ___ actors who weigh all available ___ and choose the one that maximises their wellbeing. In practice, human decision-making is strongly ___ by cognitive shortcuts and biases that produce ___ and systematic errors. One of the most powerful findings of behavioural economics is the importance of framing and ___ settings: people tend to accept the choice that has been pre-selected for them, regardless of whether it is the best option for their circumstances.