Answer:
1a. To collect and remove waste materials from the body.
2c. Urinary bladder.
3d. Urea
4c. Remove urea and excess water.
Step-by-step explanation:
The main function of our excretory system is to collect and remove waste materials from our body because these waste materials are toxic and cause damaged our body. Urinary bladder is the organ that stores urine. Urea is present in the urine under normal conditions of the body which is waste material produced our body. The main function of kidney is to remove urea and excess water from our body.