Final answer:
Sentence 3 best supports the author's point about challenges in census accuracy by listing specific groups that are hard to count, highlighting the significant task of enumerating all residents.
Step-by-step explanation:
The sentence that best supports the author's point that it can be difficult to get an accurate census count is sentence 3: "People living in rural areas, the homeless and children who split their time between two homes present challenges to getting an accurate count."
This sentence specifically lists groups of individuals who are challenging to enumerate accurately due to factors such as mobility, lack of stable residence, and living situations that don't align neatly with traditional counting methods.
Understanding these complexities helps explain why census accuracy is a monumental task and supports the notion of the census tending to understate minority populations and those living in non-traditional household arrangements.