When using a microscope to view cells you obtained from scraping under your fingernails, you notice that the cells lack nuclei; therefore, you conclude that the cells must be a type of cell.

Bacteria

Explanation:

There are two kinds of cells found in/on the human body that lacks nucleus

Since the material observed under the microscope was scraped from under the finger nails and there was no indication of broken skin, it is likely that the observed cells are bacteria.

because of

you didn't give any options but heres what i can tell you: an inference is likely to change based on additional observations. the latter is something that you have seen or sensed using your sensory organs while the former is like a conclusion out from what you have observed.