The picture represents the excretory system. which is represented by the x?

Since you have not provided a diagram, I cannot provide you with a specific answer. However, I have attached a picture of the excretory system that you could use for reference to get x.

The excretory system mainly consists of:
1- kidneys
2- Renal vein
3- Renal artery
4- Adrenal gland
5- Vena cava
6- Dorsal aorta
7- Ureter
8- Urinary bladder
9- Urethral sphincter
10- Urethra

Hope this helps :)

Temperature and pressure