Which statement about blood alcohol concentration (BAC) is true?

Introduction / Context:
Blood alcohol concentration (BAC) is a measure of how much alcohol is present in a person's bloodstream. It is an important concept in health education, road safety, and law enforcement. This question asks you to identify the correct statement related to BAC, focusing on what factors affect it and what common myths are incorrect.

Given Data / Assumptions:

BAC is defined as the amount of alcohol in the blood, usually expressed as a percentage.
The question compares statements about hangovers, methods to reduce BAC, and factors affecting BAC.
We assume general public health knowledge as taught in school and awareness programs.

Concept / Approach:
BAC depends on several factors, including how much alcohol a person consumes, how quickly they drink, their body weight, sex, metabolic rate, and whether they have eaten food. Males and females of the same weight may reach different BAC levels from the same number of drinks due to differences in body composition and enzymes that metabolize alcohol. In contrast, drinking coffee or exercising does not significantly speed up the removal of alcohol from the body. Hangover severity is influenced by many factors and is not a simple function of BAC alone.

Step-by-Step Solution:
Step 1: Recall that BAC is affected by body size, gender, and rate of drinking. Step 2: Evaluate the claim that coffee or exercise lowers BAC quickly; this is a common myth. Step 3: Consider whether hangover severity always rises directly with BAC; it does not always do so in a strict, predictable way. Step 4: Choose the statement that accurately reflects known factors affecting BAC, which is the influence of body size and gender.

Verification / Alternative check:
Health education materials and road safety campaigns routinely emphasize that BAC varies by weight and sex and that only time allows the body to metabolize alcohol. Coffee, cold showers, or physical activity may make a person feel more alert but do not remove alcohol faster. This confirms that factors like body size and gender are true influences on BAC, while quick fixes are myths.

Why Other Options Are Wrong:
Hangover severity: Although higher drinking levels can increase risk of hangovers, the relationship is not absolute or guaranteed, so this statement is oversimplified and misleading.
Coffee and exercise: These do not significantly reduce BAC; the liver breaks down alcohol at a relatively fixed rate over time.
None of the above: This is wrong because at least one statement, regarding body size and gender, is accurate.

Common Pitfalls:
A common mistake is believing in quick cures for intoxication such as coffee or strenuous activity. Another pitfall is assuming hangover severity is a direct and simple measure of BAC, which ignores individual differences, hydration, and the type of alcoholic beverage consumed. Careful reading and reliance on scientific facts help avoid these misconceptions.

Final Answer:
The correct statement is that blood alcohol concentration is influenced by factors such as body size and gender.