The most likely connotation of the word relaxing in the sentence is:
C. Tranquil.
When the speaker says: "I'm looking forward to a relaxing afternoon by the pool", he means he can't wait to spend a few hours by the pool without any source of stress or disturbance.
Other possible connotations would be: serene, placid, peaceful and calm.
Theme A) the moment of greatest tension; the turning point Conflict B) the meaning or life lesson Climax C) the development of complications Rising action D) the struggle in the story
