The excretory system of human beings includes a pair of ............, a pair of ........... a ........... and a .......... which helps in the removal of metabolic wastes from the human body.

The correct option is A kidneys, ureters, urinary bladder, urethra

• A pair of human kidneys are the major organs for excretion.
• They are bean-shaped organs located on either side of the backbone at about the level of the stomach and liver.
• Paired tubes called ureters carry waste products from the kidneys to the urinary bladder for storage till micturition.
  
• During micturition, urine is excreted through the urethra.

So, the correct answer is option A.