Concept:Photosynthesis is the process by which green plants use sunlight, water, and carbon dioxide to create their own food (glucose) and release oxygen.Explanation:To perform photosynthesis, plants need specific ingredients. These are:1. Carbon Dioxide ($CO_2$): Plants take in carbon dioxide from the atmosphere through tiny pores in their leaves called stomata.2. Water ($H_2O$): Water is absorbed from the soil by the roots and transported to the leaves.3. Chlorophyll: This is a green pigment found in chloroplasts within plant cells. Chlorophyll's main job is to capture light energy from the sun.4. Sunlight: This provides the energy needed to drive the entire process.The overall chemical reaction for photosynthesis is:$$6CO_{2} + 6H_{2}O \xrightarrow{\text{Light Energy, Chlorophyll}} C_{6}H_{12}O_{6} + 6O_{2}$$Here, $CO_2$ is carbon dioxide, $H_2O$ is water, $C_{6}H_{12}O_{6}$ is glucose (the plant's food), and $O_2$ is oxygen.Therefore, the essential factors for photosynthesis are Carbon Dioxide, Water, Chlorophyll, and Sunlight.Answer:B. $CO_2, H_2O, \text{Chlorophyll}, \text{Sunlight}.$