Final answer:
A lower standard deviation of 1 would give you the highest position within the class for a score of 75 on an exam with a mean of 70, as it indicates your score is a significant deviation from the mean.
Step-by-step explanation:
On an exam with a mean of 70, if you have a score of 75, the standard deviation that would give you the highest position within the class, or the best score relative to others would be option a) 1. The reason for this is because standard deviation measures the amount of variation or dispersion in a set of values. A lower standard deviation means that most of the numbers are close to the mean (70, in this case), so a score of 75 is farther from the mean in comparison to a higher standard deviation.
For example, if the standard deviation is 5 (option b), scores are more spread out, and it's more likely others have scored close to or above your 75. If the standard deviation is 10 (option c), scores are even more spread out, and your score is less significant as it's only half a standard deviation above the mean. However, with a standard deviation of 1, your score is 5 standard deviations above the mean, which is a significant deviation, making your score much more exceptional in this context.