Hello. You did not present the source A to which the question refers. Which makes it impossible to elaborate an answer with accuracy. However, I will try to help you in the best possible way.
First of all, we must emphasize that Nixon's policy towards Vietnam was to equip and train the South Vietnamese army, while gradually decreasing the number of American troops in the country.
Although this policy was accepted by many citizens, others criticized the way it had been done, complaining about the economic expense and the stimulation of the war that this policy presented. If source A, to which the question refers, presents these or other complaints, you can say that this source criticizes Nixon's policy.