The risk premium in country A is less than the risk premium in country B. This is because studies have shown that risk aversion tends to increase as people age. In other words, older individuals are generally more cautious when it comes to taking on risk, and therefore require a higher return to compensate for the additional risk they are taking on. This is often referred to as the 'risk premium'. Given that the average age in country B is significantly higher than in country A, it can be inferred that the residents of country B would require a higher risk premium than those in country A. This is because the older residents of country B would be more risk averse, and therefore require a higher return to compensate for any additional risk they take on. Therefore, the risk premium in country B would be higher than in country A.

Choice A is incorrect. The risk premium cannot be equal in both countries because the average age of residents, which influences risk aversion, differs significantly between the two countries. Older individuals tend to be more risk averse and hence demand a higher risk premium.

Choice B is incorrect. This choice suggests that the risk premium in country A is greater than in country B, which contradicts the general understanding that older individuals are more risk averse and therefore require a higher risk premium.

Choice D is incorrect. This choice incorrectly assumes that the risk premiums in both countries are equal to 1, without considering any factors such as age or level of risk aversion among residents.