The correct option is C Ricinus communis
The castor oil plant (Ricinus communis) is a species of flowering plant in the spurge family, Euphorbiaceae. It belongs to a monotypic genus, Ricinus, and subtribe, Ricininae. The evolution of castor and its relation to other species are currently being studied using modern genetic tools. Castor seed is the source of castor oil, which has a wide variety of uses. The seeds contain between 40% and 60% oil that is rich in triglycerides, mainly ricinolein. The seed also contains ricin, a water soluble toxin, which is also present in lower concentrations throughout the plant. So, castor oil is obtained from Ricinus communis and not from Cocos nucifera (coconut), Sesamum indicum (sesame) and Brassica campestris (mustard).
Therefore, the correct answer is option C.