What questions do the naysayers ask in Dr. Martin Luther King Jr.'s "Letter from the Birmingham Jail"?

When Dr. Martin Luther King, Jr. was arrested and put into jail in Birmingham, Alabama, on April 12, 1963, he received a copy of the April 13 edition of the Birmingham Post Herald, which published a public letter from eight local clergymen who criticized King, calling his demonstrations “unwise and untimely.” King responded to this letter with counter-arguments to their points:
King is accused of being an "outsider" who should not have come to Birmingham. 
It is noteworthy that Dr. King met on occasion with the Reverend Fred Shuttlesworth, who co-founded the Southern Christian Leadership Conference with King. In 1963, Rev. Shuttlesworth invited King to Birmingham, saying, "If you come to Birmingham, you will not only gain prestige, but really shake the country. If you win in Birmingham, as Birmingham goes, so goes the nation." When Dr. King responded to the "naysayers," he pointed to his organizational ties with Birmingham to which he had come previously to meet with Rev. Shuttlesworth.
King adds that he "cannot sit idly by in Atlanta and not be concerned about what happens in Birmingham" because there is an interconnectedness between all people who are treated unjustly.
The clergymen urge Dr. King to wait for the appropriate time.
King responds that "injustice is here," and non-violent action is necessary. He says that whenever injustice exists, it must be confronted because historically privileged groups never willingly relinquish their power. Instead, King says privileged groups only respond if there is a stirring of people's consciences, or some other tension that demands resolution. Therefore, the demonstrations were appropriately timed.
Specifically, King alludes to the promises of certain business leaders to remove the discriminatory signs from store and restaurant windows. After a while, signs which were previously taken down reappeared. Later, the SCLC learned the mayoral election was soon to occur, so they postponed action. When it was announced that Eugene "Bull" Connor was running, "We had no alternative except to prepare for direct action." He adds, “justice too long delayed is justice denied.”
The clergymen ask Dr. King why he has chosen "direct action" and not negotiation.
In response to this question, Dr. King contends direct action is the what leads to negotiation. Unless the city leaders of Birmingham thought they needed to stop the action, they would not even consider negotiation.

The purpose of our direct action program is to create a situation so crisis-packed that it will inevitably open the door to negotiation. 

As support for this argument, Dr. King alludes to the stirring of the minds of the Greek people by the great philosopher Socrates, who felt it necessary to create a tension in them to release them from their myths and half truths so they could move to "the unfettered realm of creative analysis and objective appraisal."
The clergymen ask why the SCLC did not wait to negotiate with Mr. Boutwell, the new mayor of Birmingham, before taking action.
King argues that, while Mayor Boutwell is not as radical as "Bull" Connor, he, too, is a segregationist who desires to maintain the status quo. Therefore, nothing would change unless action was taken.
Dr. King concludes, 

My friends, I must say to you that we have not made a single gain in civil rights without determined legal and nonviolent pressure. Lamentably, it is an historical fact that privileged groups seldom give up their privileges voluntarily.
https://www.africa.upenn.edu/Articles_Gen/Letter_Birmingham.html