She was sceptical about the safety of the new drug.

sanguine
hopeful
certain
doubtful

The correct answer is D. doubtful.

Skeptical means having doubts or reservations about something. Hopeful means feeling confident that something good will happen. Certain means feeling sure about something. Sanguine means optimistic or cheerful.

In this case, the woman is doubtful about the safety of the new drug. She is not sure if it is safe, and she is not confident that it will not have any negative side effects.