Answer:
C . Brute strength cannot defeat faith and courage.
Step-by-step explanation:
Goliath is known to be a man of stature with great strength. However, the story of David is that, with faith that he can win, and with the courage to carry out the task, he can accomplish what is thought to be the impossible feat, which is to kill the champion of the Philistine army.
Some of the other answers are correct, but is not the best summary of the THEME in itself. For example, slingshots are truly effective weapons of it's day and age, being easy to train with and effective against not only unarmored but also poorly armored individuals. Highly trained slingshotters are able to hit unarmored parts, and proved to be extremely effective in certain cases. B is correct if you are to look through the lens of Goliath rather than David. On many accounts following his death, Goliath understimated his opponent, and even taunted the Israelite army for "sending out a dog to fight". He was sorely mistaken, and that led to his downfall.
A is the only answer that is definitely not correct, as there was no kindness involved, unless putting someone to eternal sleep is the hidden kindness for the pains of this world.