Answer :
Plant because plants are the main autotrophs, with a few exceptions however your extra description of cell walls guarantees this is a plant.
Answer: The correct answer is Plantae kingdom.
A cell with chloroplast and a cell wall made of cellulose would likely belong to plantae kingdom. This is because cell wall of plants is primarily made up of cellulose, which is a carbohydrate that provides rigidity to the cell wall.
Chloroplast is a specialized membrane bound organelle present in green plants and algae. It is the site of synthesizing food through photosynthesis.
Thus, Plantae kingdom is the right answer.
