What is a sub-select statement

A．a select statement that selects a subset of fields in a table

B．a select statement that returns a subset of the data in a table

C．a select statement that appears within another select statement

D．a select statement that returns a subset of the constraints on a field

不属于反思目的的是（）。

A.提高教师自我教学意识

B.增强自我指导

C.自我批评的能力

D.促进学生更好的发展