A study of a math program implemented in several pre-schools indicates

(A) Most parents send their children to preschool for social development and do not have a clear idea about what types of education they want for their children.

This is irrelevant

(B) Cognitive abilities of 3- to 5-year-old children are constantly changing.

The argument is not concerned with cognitive abilities. We are talking about math here.

(C) The children in the pre-schools that were studied had previously been exposed to another math enrichment program.

It suggests that other students also underwent a math enrichment program. That program didn't help the children. So, introducing a math program may also not help. This weakens the argument.

(D) Children are not really interested in enrichment programs in preschool.

This is not relevant

(E) The cost factor needs to be specified and established before a large scale program can be undertaken.

Cost factor is out of scope

IMO OA should be C

A study of a math program implemented in several pre-schools indicates that children who received the specialized Math Plus math education between the ages three and five had significantly higher math scores in 3rd and 4th grade than their classmates who did not receive this instruction. The proponents of the math argue that the introduction of this program for all children age three to five will significantly improve their chances for success in school.

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

(A) Most parents send their children to preschool for social development and do not have a clear idea about what types of education they want for their children. Incorrect

irrelevant to argument

(B) Cognitive abilities of 3- to 5-year-old children are constantly changing. Incorrect

this can be applicable for all children's

(C) The children in the pre-schools that were studied had previously been exposed to another math enrichment program. Correct

that is reason they scored better, not for author referred program

(D) Children are not really interested in enrichment programs in preschool. Incorrect

contradicts with argument

(E) The cost factor needs to be specified and established before a large scale program can be undertaken. Incorrect

irrelevant

A study of a math program implemented in several pre-schools indicates that children who received the specialized Math Plus math education between the ages three and five had significantly higher math scores in 3rd and 4th grade than their classmates who did not receive this instruction. The proponents of the math argue that the introduction of this program for all children age three to five will significantly improve their chances for success in school.

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

(A) Most parents send their children to preschool for social development and do not have a clear idea about what types of education they want for their children.
Children idea has no influence on the conclusion
(B) Cognitive abilities of 3- to 5-year-old children are constantly changing.
Can hold for it ,but doesn’t seem so close to conclusion
(C) The children in the pre-schools that were studied had previously been exposed to another math enrichment program.
So it means these children had already some base of mathematics, not because of preschool maths education.
Strong option
(D) Children are not really interested in enrichment programs in preschool.
Same as A, no affect on conclusion
(E) The cost factor needs to be specified and established before a large scale program can be undertaken.
Irrelevant in this context

Final answerC

A study of a math program implemented in several pre-schools indicates that children who received the specialized Math Plus math education between the ages three and five had significantly higher math scores in 3rd and 4th grade than their classmates who did not receive this instruction. The proponents of the math argue that the introduction of this program for all children age three to five will significantly improve their chances for success in school.

So, the conclusion is that the "introduction of this program for all children age three to five will significantly improve their chances for success in school. ". Which means that the author is assuming that the specialized Math Plus math education is actually causing the improvement in success.

We can weaken it by showing alternate an cause or cause but no effect ( many students in other schools took the specialized Math Plus math education but received a lower grade etc. Now lets look at the options

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

(A) Most parents send their children to preschool for social development and do not have a clear idea about what types of education they want for their children.
No this statement does not weaken the argument. The parents opinion or idea does not matter in this argument. Eliminate

(B) Cognitive abilities of 3- to 5-year-old children are constantly changing. Yes this may be true, but in no way is this statement affecting the argument Eliminate

(C) The children in the pre-schools that were studied had previously been exposed to another math enrichment program.: Now if those students were already exposed to another program , that other program may have been the cause of the improvement in grades ( Alternate cause as already mentioned above). - Correct

(D) Children are not really interested in enrichment programs in preschool. Again the interest of students is not considered in this argument. Eliminate

(E) The cost factor needs to be specified and established before a large scale program can be undertaken. We are not taking about the feasibility or cost factor in the argument. Eliminate