In an experiment in Canada, ten-year-old children were...

Câu hỏi: Read the following passage and mark the letter A, B, C or D to indicate the correct word or phrase that best fits each of the numbered blanks from 25 to 29.
In an experiment in Canada, ten-year-old children were put in classes of four sizes: 16, 23, 30 and 37 children in (25) ___________class. Their teachers said that the smaller classes would result in more individual attention and better marks. However, when the children were (26) ___________, those in the smaller classes didn't get higher marks than the others, except in mathematics. Moreover, children in the larger classes said they liked school (27) ___________as much.
Perhaps the most surprising result was the difference between what teachers expected and the actual results obtained. More than 90% of the teachers expected the smaller classes to (28) ___________well.
After teaching these smaller classes, over 80% of the teachers thought the pupils had done better. However, according to the researchers, nothing of the (29) ___________happened. Class size seemed to make a difference only to the teachers' own attitudes - and not to the results they obtained.
(Source: "Longman Tests in Contexts" by J.B. Heaton)
The word or phrase which best fits the gap (27) is...
A. only
B. so
C. just
D. also