Which sentence states a fact?

 - Dione Lucas was the first woman to graduate from the cooking school Le Cordon Bleu in Paris.
 - Graduates of the Parisian cooking school Le Cordon Bleu make the most delicious meals.
The first sentence states a fact.
Dione Lucas was the first woman to graduate from the cooking school Le Cordon Bleu in Paris.
It can be proved by reading about the history of Le Cordon Bleu.
The second sentence states an opinion.
Graduates of the Parisian cooking school Le Cordon Bleu make the most delicious meals.
Most delicious shows what a person believes, thinks, or feels. Another person might have a different opinion about what counts as the most delicious meals.