You examine a population of dividing cells with an electron microscope, and you see a large, floppy, circular string near the center of the cell that seems to be tangled with another floppy circular string. deducing that the strings are the replicating dna of the cell, you determine that the cell is a prokaryote and is undergoing

Binary fission

Explanation:

Prokaryotic cells do not have a nucleus. Binary fission is one of the methods of asexual reproduction in them. During the process, replication of circular DNA begins at the origin of replication and continues as the replication is bidirectional and the enzymes synthesize DNA in both directions.

As the replication comes to an end, the cell appear to have two circular DNA molecules entangled with each other. The septum grows towards the inner side as the chromosomes move toward opposite ends of the cell. This is followed by the formation of septum completely through the cell center, to make two separate cell chambers.

it would be c. xylem.