Final answer:
It is true that the human eye can see particles as large as 900 micrometers; this size is within the visual capabilities of an unaided eye since it can typically see objects down to about 100 micrometers.
Step-by-step explanation:
The statement that an unaided eye can see particles of 900 micrometers is true. For some perspective, consider that most microorganisms are much smaller than this size, often requiring a microscope for proper visualization. The smallest objects that the unaided human eye can typically see are about 100 micrometers in size, which means particles of 900 micrometers are well within the range of visibility for a normal healthy human eye.