You will be given a definition of a task first, then some input of the task.
In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Among the entities, try to find the best entity that is most likely to fill in "_" and classify the answers based on options.

(CNN) -- Fifteen years ago, men who were suffering from impotence received a beacon of hope in the form of a little blue pill. Wednesday marks the 15th anniversary of Viagra's FDA approval in the United States. Viagra currently holds 45% of the sexual dysfunction market share, with competitor Cialis in close second, according to industry researcher IMS Health. There were 8 million Viagra prescriptions written in 2012 with total sales of about $2 billion. But how did a drug that was originally tested for the treatment of heart problems end up in bedrooms across America? Take a look back at Viagra's history.Viagra was approved by the FDA on March 27, 1998British scientists working for Pfizer first created the drug in 1989Since then three major competitors for Viagra have been approved 
 Questions:The side effects for _ are similar to Viagra, and men with heart problems or abnormal blood pressure are advised against taking it. (A) CNN (B) Viagra (C) FDA (D) United States (E) Cialis (F) IMS Health (G) America (H) British (I) Pfizer
Output:
(E)