Answer:
C. Figured bass symbols
Step-by-step explanation:
The Baroque period refers to the period after the Renaissance music era and it was a period that typically involved the composition of western art music between 1600 and 1750.
During the Baroque period, songs were written in a particular key such as the figured bass and this style was known as the common-practice tonality.
A figured bass can be defined as a type of musical notation that typically involves the use of symbols and numerals (numbers) above and below to represent or denote chords, non-chord tones and intervals that are being played on instruments such as lute, piano, organ etc, with respect to the bass note.
In this scenario, a scholar examines a score trying to determine when it was written. Therefore, the clue which might suggest that it was written during the Baroque period is the figured bass symbols.