Final answer:
A toxic level of alcohol generally refers to a BAC well above the legal limit for driving; option (d) 400 to 600 mg/dL is considered to be a toxic level, potentially resulting in unconsciousness or death.
Step-by-step explanation:
The toxic level of alcohol in a human's blood alcohol concentration (BAC) depends on several factors, but generally, levels well above the legal limit for driving, which is 0.08%, are considered toxic. In acute cases, severe alcohol intoxication can result in unconsciousness or even death. Based on the information provided, the option that falls into the fatal range would be (d) 400 to 600 mg/dL. This corresponds to a BAC of about 0.40% to 0.60%, which is dangerously high and may be lethal.
It's important to be aware of the rate at which the liver can metabolize alcohol, which is approximately 15 mg/dL per hour. Exceeding this rate can quickly lead to alcohol toxicity since the body cannot metabolize the ethanol fast enough, leading to accumulation and increased BAC levels. It's also critical to note that individual rates of metabolism can vary, and some people might experience toxic effects at lower concentrations.