Final answer:
Jeremiah likely felt sentimental while looking back through his year high school yearbook, which is a feeling of tenderness and nostalgia for the past.
Step-by-step explanation:
As Jeremiah looked back through his yearbook pictures, remembering all the fun and hard work of high school, he felt sentimental. This emotion reflects a wistful or tenderly affectionate feeling for the past, typically for a period or place with happy personal associations. The term 'amorous' indicates strong feelings of love, usually in a romantic context, which does not align with the reminiscence of high school memories. 'Amiable' describes a person's pleasant and friendly disposition, not an emotional state. 'Euphonious' refers to a sound that is pleasing to the ear, which is unrelated to the feelings of nostalgia that Jeremiah might have had while looking through his yearbook.