Answer:
(C) as the speaker becomes more familiar with the river, his attitude toward it becomes more practical.
Explanation: The passage suggests the chemistry forged when one continously indulge in a certain action. According to an excerpt from the passage, the speaker said in quote "Now that I had master the language of this water and had come to know every trifling feature that bordered the great river as familiarly as I knew the letters of the alphabet". This emphasizes that the familiarity formed as a result of long and continued association makes them have a practical relationship.