Give an example of a statement that best describes the rhyme scheme of "A Thought on the Inestimable Blessing of Reason".

I don't know if you have any options, but I'd say that the rhyme scheme of this poem is aabbcc, etc. - this means that two lines rhyme, and then the next to lines rhyme, etc. The entire poem is written in the octosyllabic couplet, meaning that each line has 8 syllables (an octave), and the term couplet refers to the rhyme - that every two lines rhyme.