No regrets -- but it's one point for the Wet Invaders.
4. Stopping roof leaks is best accomplished by:
B. Repairing roofing, parapets, and overhangs that allow moisture to get in.
We always recommend repairs that extend the longevity of historic materials.
The alternatives are both bad here. Using black tar ("goop") is not only very temporary, the petroleum distillates in asphaltic compounds can corrode metal flashing and roofing nails. Once asphaltic mastic is on historic materials, it is difficult to remove and looks unsightly too! You're better off covering deteriorated areas with a tarpaulin--temporarily--until a proper roof repair can be made. Slate roofs, in particular, can last a long time if properly maintained and repaired.
The third option, C. Replacing the entire roof with all new materials, goes against basic historic preservation princples!
please try the final question!