A rhyme scheme can be defined as the sound at the end of each verse in a poem. This is a repetitive sound that occurs at the end of each verse in a song or poem. There are various types of rhyme schemes in literature such as internal rhyme, slant rhyme, etc.
In the given lines, the end of each verse rhyme with each other, that is <em>sky </em>and <em>high. </em>Therefore, the correct answer is option A.
Robert Frost often uses traditional poem structure such as iambic pentameters or similar when writing poems even though his themes are modernist. He sometimes even wrote sonnets.