Q: It must be difficult producing a consistent product.
A: There are seven hundred components in Scotch whisky. Some have a low flavour threshold but the interplay amongst those that have flavour is tremendous. Producing a consistent single malt is very difficult.
End of excerpt.
A) you can assume no sherry casks at all were used,
C) even if they were used you can assume it is batul
Sherry cask