Which doctrine did the Council of Constantinople I incorporate into the Nicene Creed?

The Council of Constantinople I, which convened in 381 AD, aimed to address theological disputes and to further articulate the Christian understanding of the Trinity. One of its significant contributions was the clarification and affirmation of the divinity of the Holy Spirit.

During this council, the Nicene Creed was expanded to include a more explicit declaration about the Holy Spirit, stating that the Holy Spirit is "the Lord, the giver of life, who proceeds from the Father." This addition emphasized the Holy Spirit’s co-equal status within the Trinity, alongside God the Father and God the Son, thereby reinforcing the belief in the divine nature of the Holy Spirit.

The other choices reflect important theological concepts but were not the focus of the Council of Constantinople I. The resurrection of the body is a fundamental Christian belief, original sin outlines theological anthropology, and the supremacy of the Pope pertains to ecclesiastical hierarchy and authority, none of which were specifically addressed or integrated into the Nicene Creed during this council.