Who, according to king, will not like the idea that competent writers can be made into good writers?

many writing teachers
most parents
typical vacationers
sophisticated poets

According to King, many writing teachers will not like the idea that competent writers can be made into good writers. 
This is his exact quote:
"...while it is impossible to make a competent writer out of a bad writer, and while it is equally impossible to make a great writer out of a good one, it is possible, with lots of hard work, dedication, and timely help, to make a good writer out of a merely competent one."
So writers that have some merit will become good writers after a time of practice and hard work.

A, to visit her father at his army camp