IMO A, correct me if I am wrong:
According to an esteemed psychologist, the only way to maintain a positive frame of mind is to discard all negative thoughts and their sources; not to think about them, worry about them, analyze them, but to simply discard them.
A. not to think about them, worry about them, analyze them, but to simply discard them
----- correct, parallel construction & after semicolon we need an independent clause.B. not to think about them, to worry about them, to analyze them, but simply discarding them
-------incorrect, no parallel constructionC. not thinking about them, worrying about them, analyzing them, but simply discarding them
-------incorrect, after semicolon we need an independent clause.D. not thinking about them, worrying about them, analyzing them, but to simply discard them
-------incorrect, after semicolon we need an independent clause.E. not thinking about them, worrying about them, analyzing them, but simply to discard them
-------incorrect, after semicolon we need an independent clause.