The poem "I Look into My Glass" by Thomas Hardy explores themes of longing, introspection, and the passage of time. In this context, the most appropriate option that reveals elements of Romanticism through inner emotional struggles is:
B) the inner struggles of the subject, longing for his heart to become cold.
This option emphasizes the emotional and psychological exploration that is characteristic of Romanticism, focusing on the inner conflict and the desire for detachment from emotional pain.