Question

in which specimen were cells first identified? microorganism cork bark dna mitochondrion

Explanation:

In 1665, Robert Hooke used a primitive microscope to observe cork bark. He saw small, box - like structures and named them "cells". Microorganisms were observed later by Antonie van Leeuwenhoek. DNA was identified much later through biochemical studies. Mitochondria were also discovered after the initial identification of cells. So the first specimen in which cells were identified is cork bark.

Answer:

B. cork bark