The correct option is C the spirit of the bamboo
Option C: As mentioned in the lines: "I wish you, Friend, the finest thing that I can wish for you... just a spirit of bamboo.", the poet wishes for his friend the spirit of the bamboo. Hence C is correct.
The words 'agility', 'height' and 'slenderness' are not mentioned in the poem. The poet does not wish for these aspects of the bamboo, for his friend.
Hence options A, B and D are incorrect.