The Reading Basics courseware was recently used in a fourth grade clas

The Reading Basics courseware was recently used in a fourth grade classroom. After just twelve weeks, over 50% of the class was able to read at a fifth grade level. Teachers at every elementary school in the country should purchase our program and incorporate it into their teaching materials to accelerate the acquisition of reading skills by their students.

Which of the following, if true, would most seriously weaken the above conclusion?

(A) Twelve weeks is not the length of a standard semester at most elementary schools.

Less than twelve or more than twelve- we do not know -Eliminate

(B) The publisher of the reading basics course does not possess a teaching certificate or any experience as an elementary school instructor.
Irrelevant - How does it matter whether publisher possess a teaching certificate or not

(C) In a similar experiment, the majority of a third-grade classroom was only able to read at a fourth-grade level after over fourteen weeks of instruction using the reading basics program.

Irrelevant- The set is changed -Eliminate

(D) Not every elementary school in the country can afford to purchase the courseware.
Does not matter if one in million schools can't purchase- We do not know the figure -Eliminate

(E) other fourth grade classes commonly experience similar reading comprehension improvements without using the reading basics course.
Yes, Even without the course results are same

Cause is removed, Effect is same - Correct choice

(E) is correct IMO