Final answer:
The most commonly affected part of the urinary tract in a UTI is the bladder, although the urethra and ureters can also be affected. Bacteria are the most common cause of UTIs.
Step-by-step explanation:
The urinary tract is the pathway that urine travels through when it is eliminated from the body. It consists of several parts including the kidneys, ureters, bladder, and urethra. In the case of a urinary tract infection (UTI), the most commonly affected part is the bladder. However, UTIs can also affect the urethra and ureters. Bacteria are the most common cause of UTIs, and they can make their way into the urinary tract through the urethra, causing infection.