The answer is B. The linking verb is 'is'. Linking verbs do not show any action but they connect the subject of a sentence to a word that gives information about that subject.
The two lines that reflect the theme of growth and maturation in this excerpt are: "Season of mists and mellow fruitfulness, Close bosom-friend of the maturing sun" and "Or by a cider-press, with patient look, Thou watchest the last oozings, hours by hours". The first line expressed the theme by two key phrases "mellow fruitfulness" and "maturing sun", as fruitfulness is often use as a theme for spiritual maturity. The second line tell us about "with patient look" and watching the last oozings hours by hours, those are characteristics of elderly people that patiently look how the world around them moves, while they live they last days quietly.
