Text Completion

Can anyone help me with this question?

Source: Wizako https://practice-questions.wizako.com/gre/verbal/text-completion/text-completion-while-5.shtml

I think the first blank is A, because

while is (-ve)
differ in usage(on the right side of blank)
so blank must be opposite of differ in usage, i.e., they don’t differ in usage and can be iterchanged.

for blank 2, I went with f
because of the word “any number”

for blank 3, I went with g
since h doesn’t make sense and although cannot be used because I don’t see 2 opposing words.

Is the answer: - A,F,G ?

B, E, H is the correct answer.
https://practice-questions.wizako.com/gre/verbal/text-completion/text-completion-while-5.shtml
(Reference)