Which of the following is the defining feature of a hall church such as saint-savin-sur-gartempe?
a. it has low aisles and tribune galleries.
b. the aisles are approximately the same height as the nave.
c. it has a series of windows in the apse.
d. it has low aisles but no tribune galleries.

B)The aisles are approximately the same height as the nave.

Explanation:

The Saint-Savin-Sur-Gartempe is a church (an Abbey to be precise) built in the Romanesque style (11th to 12th century), and because of that, it is small in comparison to the Gothic churches, and its aisles are narrow, sustained by columns and with the same height as the nave, to obtain a strong structure.

i'm not sure i completely understand your question, but i will do my best.

i think the answer you are looking for is sequence. (see below)

a repeated melodic fragment would be best defined as repetition, while repeated chords (different or the same) could be a chord progression. however, you then mentioned the chord and melodic fragment beginning on higher or lower pitches, in that case, the answer could be best defined as a sequence. the definition of a sequence is as follows: "the restatement of a motif or longer melodic (or harmonic) passage at a higher or lower pitch in the same voice."

let me know if this !