For a reader to two or more things, the reader must consider how the things are different.

The correct answer is to compare.

For a reader to compare two or more things, the reader must consider how things are different.

Another option for the sentence could be to contrast. Compare or contrast are equally right,

A good reader needs to understand the different concepts contained in a text. If the reader does not understand the differences it would be difficult for it to have a clear idea and reach a valid conclusion. So, in order to do this, the reader has to compare ideas, propositions, theories or any other element that helps him recognize the differences.  

the correct answer is "the rhythm and rhyme scheme add to an eerie and suspenseful tone". poetry is literature written in stanzas and lines that use rhythm to express feelings and ideas. poets will pay particular attention to the length, placement, and grouping of lines and stanzas. this is called form. lines or whole stanzas can be rearranged in order to create a specific effect on the reader.