Why Are Many Researchers Troubled by the Results of Studies

Why are many researchers troubled by the results of studies on what determines the success of early childhood program enrollees later in life?

A) The most important factors, parental involvement and socioeconomic status, are outside of teachers' control.
B) The most common early childhood teaching methods tend to be associated with lower levels of success later in life.
C) Most children are not enrolled in high-quality programs that are likely to significantly improve their chances of success later in life.
D) There is no evidence that early childhood programs positively affect the lives of enrollees after the complete elementary school.