Answer: Plus or minus 1 standard deviation from the mean.
Step-by-step explanation:
According to the Empirical rule,
If the population is normally distributed then, about 68% of the population lies within 1 standard deviation from the mean value.
Here, the data shows 68% percent of the area under the normal  distribution.
This is equivalent to "plus or minus 1 standard deviation from the mean."
Hence, the correct option is : plus or minus 1 standard deviation from the mean.
