When you have a question about fact or opinion, look carefully at what can be proven and if there are words in the sentence which reflect opinion. For example, the first sentence is fact which can be proven in any pizza place.  The third  sentence is also fact which you can prove in any flower garden or field.  The second sentence, however, contains the words "more interesting" which reflects opinion.  Think of whether you find basketball more interesting than golf.  Do any of your friends dislike watching any sport?  In whose opinion is basketball a more interesting sport to watch?  Yours?  Your best friends?  This is a classic example of opinion. Learn to look for words which signal opinion such as the "more interesting" in this example.