Trying to criticize writing on the fly is possibly the single greatest barrier to writing that most of us encounter.If you are listening to that 5th grade English teacher correct your grammar while you are trying to capture a fleeting thought,the thought will die.If you capture the fleeting thought and simply share if with world in raw form,no one is likely to understand.

请问 B 是什么意思?为什么不选?
What prevent people from writing on is A
A attempting to edit as they write
B ignoring grammatical soundness

B意思是忽视语法的合理性；
选a是对的，If you are listening to that 5th grade English teacher correct your grammar while you are trying to capture a fleeting thought,the thought will die.这句话意思就是说如果你太专注于语法的正确性，那么你的这个想法就是错误的，所以b项意思正好相反，ignoring grammatical soundness正是写作时需要的，而不会是prevent people from writing on