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.

primary succession begins with a bare rock and ends with a forest secondary succession begins after a natural disaster where there is a temporary setback after a forest fire or local destruction, but the surrounding area can fill in

a and c are the answeres