Final answer:
Option (1), Heian aristocrats expressed their feelings mainly through poetry, specifically the thirty-one syllable tanka, which was an essential aspect of their cultural and social activities.
Step-by-step explanation:
During the Heian period, aristocrats conveyed their feelings predominantly through poetry, such as the thirty-one syllable tanka. This art form was essential for social connection, celebration of events, and documentation of both emotions and observations. Poetry was intertwined with the aristocracy's cultural activities and was a clear expression of personal taste and emotional communication.
Heian-era literature, such as the famed The Tale of Genji by Murasaki Shikibu, provides a wealth of insights into the emotional and cultural expressions of the time. Aristocrats carefully crafted poems and letters that reflected their education, aesthetic sense, and emotions.