On the Official Guide for GMAT Review 11th edition(page number: 640), I found this sentence:
17. None of the attempts to specify the causes of crime explains why most of the people exposed to the alleged causes do not commit crimes and, conversely why so many of those not so exposed have.
According Manhattan GMAT SANAM Pronouns, if "None" is followed by "of" then object followed by "of" determines the number of the subject and hence "None" should plural.
So why verb "explains" instead of plural verb "explain"?