It would be the number of observations is 15.
The median of the data is not 3. It's four, because both sides are symmetrical and therefore the number in the very center is the median, or 4.
The mean of the data is not 3, as again, it is symmetrical, so therefore the number in the very center is the mean, 4 again.
The range is the max - min, or 4, which is not 5.
If we count the total number of observations, 2 + 3 + 5 + 3 + 2 = 15, then we know the last one is correct.