A student achieves an 82 on the first test in a statistics course. From this, she assumes that her average at the end of the semester (after other tests) will be about 82. This is an example of （）.

A.One form of descriptive statistics uses graphical techniques
B.One form of descriptive statistics uses numerical techniques
C.In the language of statistics，the term population refers to a group of people
D.Statistical inference is used to draw conclusions or inferences about characteristics of populations based on sample data

A.organising data.
B.summarising data
C.presenting data in a convenient and informative way
D.doing all of the above