Final answer:
Speyer Cathedral underwent major rebuilding in 1080, which included the addition of groin vaults, option 4)compound piers, and window openings to the nave.
Step-by-step explanation:
The major rebuilding done to Speyer Cathedral in 1080 included the addition of groin vaults to the nave, compound piers to the nave, and window openings to the nave.
This transformation from the dark Romanesque style to the Gothic style allowed for a reduction in wall area and the installation of large windows filled with stained glass. The addition of groin vaults and compound piers provided structural support and allowed for the creation of expansive interior spaces.