Final answer:
Option (a). Ammonia (NH3) is the toxic byproduct of oxidative deamination in humans that is swiftly converted to urea to prevent toxicity.
Step-by-step explanation:
The byproduct of oxidative deamination that is toxic to humans is ammonia (NH3). Ammonia is formed during the breakdown of amino acids through the process of deamination, where the amino group (NH2) is removed. Due to its high toxicity, ammonia is rapidly converted into urea in the liver through the urea cycle, which is then excreted from the body in urine.
While urea is a less toxic compound and plays a role in the body's recovery of water, ammonia's accumulation can be fatal if not properly processed and converted due to its ability to raise the pH of body fluids and its general harmful effects on cellular function.