Why ”Bhagavad Gita AS IT IS” is Authentic?

Maharaj responds to a question about what needs to be said to people who ask, why Bhagavad Gita as it is, is authentic as compared to other Bhagavad Gita . He mentions, while other commentaries use the ascending method, Bhagavad Gita as it is does not. Bhagavad Gita as it is, is descending knowledge and hence authentic as stated in Bhagavad Gita chapter 4.