The main idea of the poem is expressed in letter a.
The makings of the sun are the things of the natural world, while the makings of the poet are poems that reflect the imaged world. In the poem Wallace Steven implies that the nature and poems share a deep affinity . "His self and the sun were one And his poems, although makings of his self, Were no less makings of the sun" this statement expresses that the poets reflect what the natural world shows becoming only one at this point.
Another statement form the poem that supports this option is when the poet writes "Ariel was glad he had written his poems. They were of a remembered time Or of something seen that he liked." The writer claims that his poems were about something he has seen and he has liked, something he has perceived in nature thus he has written about them.