Final answer:
The exact number of homeless individuals is difficult to know due to data collection challenges, the transient and varied nature of homelessness, and the tendency of homeless individuals to be hidden within communities.
Step-by-step explanation:
Understanding the exact number of homeless persons is challenging due to a variety of factors. Primarily, there are issues with data collection; many homeless people may refuse to provide demographic information (Option a) or refuse to be interviewed (Option b), making it hard to gather accurate statistics. Additionally, homelessness varies greatly from one location to another (Option c), so data cannot always be generalized across different areas. Another complication is the transient nature of homelessness; some individuals may only experience short intervals of homelessness (Option d), and as such, may not always be counted during point-in-time surveys. Lastly, homeless individuals often blend into the community (Option e) and may not be easily identifiable, especially if they are not using shelters or are residing temporarily with friends or family.
The complexities involved in measuring homelessness are further compounded by factors such as addiction, mental illness, and economic issues, which can contribute both to the likelihood of becoming homeless and the difficulty in obtaining accurate counts. High rent prices and low vacancy rates in urban areas can exacerbate the issue, making it a visible representation of the scarcity of resources (Figure 1.2 Scarcity of Resources).
In summary, the multifaceted nature of homelessness, combined with the societal and economic factors that drive it, makes identifying and assisting the homeless population a severe challenge for cities and nations around the world.