Will give brainlest excerpt from Bird Thoughts Traditional

By: Traditional
I lived first in a little house,
And lived there very well;
I thought the world was small and round,
And made of pale blue shell.

I lived next in a little nest,
Nor needed any other;
I thought the world was made of straw,
And brooded by my mother.

One day I fluttered from the nest
To see what I could find.
I said, “The world is made of leaves;
I have been very blind.”

At length I flew beyond the tree,
Quite fit for grown-up labours.
I don’t know how the world is made,
And neither do my neighbours!
What is the main image in the first stanza?

A) an unborn chick nestled inside an egg
B) a baby bird living happily in a straw nest
C) a curious bird checking out the leaves of a tree
D) a bird trying out new wings and seeing the world for the first time