The problem with population ageing is:a.there may come a time when there are not enough young people to finance or care for the oldb.increased death ratesc.increased birth ratesd.population explosion

The problem with population ageing is: a. there may come a time when there are not enough young people to finance or care for the old. This is because as the population ages, the proportion of people who are of working age decreases. This can lead to a shortage of workers, which can in turn lead to economic problems. Additionally, older people often require more care and support, which can put a strain on healthcare systems and social services.

Option b, increased death rates, is not a problem associated with population ageing. In fact, population ageing is often caused by decreased death rates, as people are living longer.

Option c, increased birth rates, is also not a problem associated with population ageing. In fact, population ageing is often caused by decreased birth rates, as people are having fewer children.

Option d, population explosion, is not a problem associated with population ageing. Population explosion refers to a rapid increase in the number of people, which is the opposite of what happens when a population ages.