Which of the following scenarios would NOT give a normal distribution?

It is likely that as the percentage of toxic substances in an environment increases, the percentage of living organisms will decrease. The amount of pollution in the atmosphere is affected by many factors, such as the location, the time of year, and the weather conditions. This means that the distribution of pollution levels is likely to be skewed or irregular, and not bell-shaped. This would be an inverse relationship and would not exhibit a normal distribution. The rest would show normal distribution.