Which feature is found in prokaryotic cells but not in eukaryotic cells?
a. cytoplasm
b. nucleoid
c. plasma membrane
d. nucleus

The correct answer is B - nucleoid.

The nucleoid is a region in a prokaryotic cell that houses the main DNA material of the cell.

In contrast to eukaryotic cells with a nucleus, prokaryote have a nucleoid where the genetic material can be found. The nucleoid is different from the nucleus in eukaryotes in that the genetic material is not enclosed in a membrane to separate it from the cytoplasm.

The nucleoid usually contains  only a single chromosome which has the cell DNA.

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]