After administering a pop quiz on graphing on the coordinate plane, in which sixty percent of his students fail, what should Mr. Marks do next?
**Options:**
1. Analyze the specific questions that most students struggled with and review those concepts in the next class.
2. Give extra homework to the students who failed to ensure they catch up with the rest of the class.
3. Assume that the material was too difficult and move on to the next topic in the curriculum.
4. Offer extra credit to all students to improve their overall quiz scores.