Which of the following is present only in plant cells?
I. A nucleus   II. A cell wall   III. A cell membrane  IV. Cytoplasm  V. Chloroplasts.

1. Cell walls exist in plant cells. It gives the plant rigidity. Animals don't have cell walls.
2. Plant cells contain chloroplast, which is involved in photosynthesis.
3.  As a result, plants are considered autotrophs. Animal cells are heterotrophs and do not have chloroplasts. 
4. Plant cells have a cell wall that surrounds their plasma membrane and offers tensile strength as well as defense against osmotic and mechanical stress. 
5. Additionally, it enables the development of turgor pressure, or the pressure of the contents of the cell against the cell wall. 
6. Chloroplasts, cell walls, and intracellular vacuoles are a few characteristics that set plant cells apart. Chloroplasts are responsible for photosynthesis, cell walls provide plants the strength to stand upright, and vacuoles control how cells handle water and store other molecules.

Hence, option A is the correct answer.