Answer:
No urinary bladder.
Step-by-step explanation:
Urinary bladder is present in pelvis, is a muscular sac like structure. The main function of the urinary bladder is storage of urine. After expel of urine, the size of urinary bladder decreases.
Birds contain light weight organs which helps them to fly. The urinary bladder is absent in birds to reduce the weight of the body. They have modified their excretory products according to the body's need.
Thus, the correct answer is option (A).