Answer:
D. The value is a statistic because it is a numerical measurement describing some characteristic of a sample.
Explanation:
A survey found that 75% of all respondents were optimistic. We consider 75% of all respondents is a sample from over all population, so it's a statistic. Value of statistics are e.g sample mean, sample proportion etc .
It is important to understand that the numerical measurement describing some characteristic of a population is called as parameter. e.g. population mean , population proportion etc. Hence, it is not correct.