The answer is -
A. Neither
An attempt was made to purify Catholic church music as a result of the deliberations of the Council of Trent.
Answer: deliberations of the Council of Trent
The element of plot that this event represents is C) turning point.
The turning point is also known as climax in the stories and it is the point when all actions start to happen it is also represented by an intense lapse of tension and drama which we can read in these lines by the words source of crying and discovers.
When we say firsthand and personal source, this would mean that the answers that you are looking for should come directly from the person him or herself who is involved in a particular issue or event. In this case, it is the diary entry that could be considered as a first hand source for a historical event. The diary is directly written by the person him or herself.