Which of the following is not a way in which an author would develop a character?
a. have other characters discuss him of her.
b. write dialouge with the character and another character.
c. let the reader know what the character is thinking and feeling.
d. introduce new events involving the character.

A. have other characters discuss him of her.

Explanation:

Having characters speaking about the main one does move forward the protagonist's arc, since it does not add a relevant layer to his/her actions, reactions, thus, avoiding any possibility of development.

It must be done through him/herself in a variety of ways:

the following key ideas correctly express the key sentence.

restate key idea: most people can learn to swim in ten short lessons.

restate key idea: the majority of water-accident victims require mouth-to-mouth breathing.

restate key idea: an empty, tightly closed gallon jug will support a tired swimmer.  

restate key idea: first aid is to prevent accidents as well as assist in rescue.

explanation: the key idea needs to have the same topic as the key sentence (drowning and safety).