Biology

The most helpful observation for classifying a cell as either prokaryotic or eukaryotic would be: B.Presence of a nucleus.

Here's why:

1.Prokaryotic cells lack a membrane-bound nucleus; their DNA is located in a region called the nucleoid.

2.Eukaryotic cells have a membrane-bound nucleus that houses their DNA.

The other observations are less definitive for this classification:

A.Shape of the cell: Both prokaryotic and eukaryotic cells can vary widely in shape. ...