All if the students in Ms. Osbourne's class like pizza. Jeff is a student who likes pizza. Therefore Jeff is in ms. Osbourne's class.

The full question should read "All the students in Miss Osbourne's class like pizza. Jeff is a student who likes Pizza. Therefore, Jeff is a student in Miss Osbourne's class. True, Falls, uncertain?" So to answer the question, it would be false. Just because Jeff likes pizza doesn't mean he would be in Miss Osburne's class. There are hundreds of students in a school who likes pizza, not all of the students would be exclusively in her classroom. The statement is a syllogism with an undistributed middle. It is not an exclusive class for people who like pizza, it is most likely a coincidence that all the students like pizza.