Are you reading the sections in the book?? This is explained literally everywhere. Answer is B.
Prices in strong markets reflects all information: historical, public, and private data.
Prices in semi- strong reflects historical information and public information.
Prices in weak-form markets include only past data.
So if markets are semi-strong, it means they don’t even reflect public data. So anything stronger than semi-strong (which is strong) would not uphold (or be efficient).