This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
Which of the following component of hydrocolloid can lead to fixed drug eruptions? 
Select and explain. 
A. CaSO4, B. Phenolphthalein, C. Na fluorititanate, D. Magnesium oxide
B: Phenolphthalein
Answer: B: Phenolphthalein 
Explanation: None