The correct options based on the information will be:
1. But also
2. No change.
3. No change.
1- Both Dorothy Sayers and Carolyn Heilbronn have written scholarly works as well as popular murder mysteries, demonstrating a diversity of talents and interests.(B) but also
2- The bookstore sold three times as many textbooks this week as it ordinarily does in an entire month.(A) NO CHANGE
3- The nineteenth-century laying of the first telegraph cables between Europe and America was a project plagued by cable breakage, financial setbacks, and overcoming logistical problems. (A) NO CHANGE