This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Dermatitis, Subject name: Dental
Most common plant implicated in the causation of dermatitis is 
Select and explain. 
A. Cotton fibres, B. Poison ivy, C. Pahenium grass, D. Ragweed
C: Pahenium grass
Answer: C: Pahenium grass 
Explanation: Pahenium dermatitis is caused by dry powder of leaves and flowers and hair-like structures (trichomes). Sesquiterpene lactones (SQLs) are the most impoant allergens responsible for ACD to pahenium. Ref Harrison20th edition pg 1234