I believe the answer you want is A.
First of all, if the story would be in chronological order, there would be no story at all. This is because the main character of the story, Anna, won't tell the narrator, her daughter, a lot about her past. "She has kept no squinted costume, no photographs, no fliers or posters from that part of her youth".
Because the narrator tells the story in the present and uses flashbacks is the reason that she can unify certain themes, such as the three times her mother saved her life because of her leaps. "I owe her my existence three times". These three leaps the narrator owes her life might be: when Anna Saves herself when she falls from the trapeze, when she falls in love with the narrator's father, and when she saves the narrator life from a fire by climbing to the room where the narrator is trapped.
Increasing or increased in quality, degree, or force by successive additions.
B is the only logical answer the rest does not fit the answer
