Cloze Passage:
When it became difficult to empirically prove that children ______ better in private schools, the attack ______ a new weapon: per unit cost of learning outcomes. Most of the learning outcome researches almost ______ fail to understand the entire ______ of education in any depth and reduces it to learning of so-called 3Rs for economic purposes.

Select the correct option for the second blank.

1. A
   learn
2. B
   study
3. C
   educate
4. D
   train