The sentence that best demonstrates the author's reason for writing is is option (b).
The sentence is “Then the Eldest Magician made a Magic with the right hand, with all five fingers of his right hand, and lo and behold, Best Beloved, Pau Amma grew smaller and smaller and smaller, till at last there was only a little green crab swimming in the water alongside the canoe, crying in a very small voice, ‘Give me the scissors!’”
Option (b) explains the reason completely and gives us full information. The language used is also formal and understandable.
Therefore, the correct answer is (b).
Learn more about Writing on https://brainly.com/question/24858866
#SPJ10